Transcutaneous analyte sensors, applicators therefor, and associated methods

ABSTRACT

The present embodiments relate generally to systems and methods for measuring an analyte in a host. More particularly, the present embodiments provide sensor applicators and methods of use with pushbutton activation that implant the sensor, withdraw the insertion needle, engage the transmitter with the housing, and disengage the applicator from the housing, all in one smooth motion. Some embodiments contemplate engagement of the transmitter with the housing after release of the applicator.

INCORPORATION BY REFERENCE TO RELATED APPLICATIONS

Any and all priority claims identified in the Application Data Sheet, orany correction thereto, are hereby incorporated by reference under 37CFR 1.57. This application is a continuation of U.S. application Ser.No. 14/976,558, filed Dec. 21, 2015, which is a continuation of U.S.application Ser. No. 13/826,372, filed on Mar. 14, 2013, now U.S. Pat.No. 9,931,065, which claims priority to U.S. Provisional Application No.61/620,152, filed on Apr. 4, 2012. Each of the aforementionedapplications is incorporated by reference herein in its entirety, andeach is hereby expressly made a part of this specification.

TECHNICAL FIELD

Systems and methods for measuring an analyte in a host are provided.More particularly, systems and methods for applying a transcutaneousanalyte measurement system to a host.

BACKGROUND

Diabetes mellitus is a disorder in which the pancreas cannot createsufficient insulin (Type I or insulin dependent) and/or in which insulinis not effective (Type 2 or non-insulin dependent). In the diabeticstate, the victim suffers from high blood sugar, which can cause anarray of physiological derangements associated with the deterioration ofsmall blood vessels, for example, kidney failure, skin ulcers, orbleeding into the vitreous of the eye. A hypoglycemic reaction (lowblood sugar) can be induced by an inadvertent overdose of insulin, orafter a normal dose of insulin or glucose-lowering agent accompanied byextraordinary exercise or insufficient food intake.

Conventionally, a person with diabetes carries a self-monitoring bloodglucose (SMBG) monitor, which typically requires uncomfortable fingerpricking methods. Due to the lack of comfort and convenience, a personwith diabetes normally only measures his or her glucose levels two tofour times per day. Unfortunately, such time intervals are so far spreadapart that the person with diabetes likely finds out too late of ahyperglycemic or hypoglycemic condition, sometimes incurring dangerousside effects. Glucose levels may be alternatively monitored continuouslyby a sensor system including an on-skin sensor assembly. The sensorsystem may have a wireless transmitter which transmits measurement datato a receiver which can process and display information based on themeasurements.

The process of applying the sensor to the person is important for such asystem to be effective and user friendly. The application process shouldresult in the sensor assembly being attached to the person in a statewhere it is capable of sensing glucose level information, communicatingthe glucose level information to the transmitter, and transmitting theglucose level information to the receiver.

SUMMARY

The present systems and methods relate to systems and methods measuringan analyte in a host, and for applying a transcutaneous analytemeasurement system to a host. The various embodiments of the presentsystems and methods for processing analyte sensor data have severalfeatures, no single one of which is solely responsible for theirdesirable attributes. Without limiting the scope of the presentembodiments as expressed by the claims that follow, their more prominentfeatures now will be discussed briefly. After considering thisdiscussion, and particularly after reading the section entitled“Detailed Description,” one will understand how the features of thepresent embodiments provide the advantages described herein.

One aspect of the present embodiments includes the realization that,with some sensors, the process of applying the sensor to the person isimportant for such a system to be effective and user friendly.Accordingly, a device configured for ease of application may bebeneficial. Similarly, a method of application is desirable if itresults in the sensor assembly readily being attached to the person in astate where it is capable of sensing glucose level information,communicating the glucose level information to the transmitter, andtransmitting the glucose level information to the receiver.

Accordingly, in a first aspect, a device is provided for applying anon-skin sensor assembly to skin of a host, the device comprising: a baseconfigured to secure a housing, wherein the housing is configured toreceive an electronics unit, wherein the electronics unit is configuredto generate analyte information based on a signal from a sensor; asensor insertion mechanism configured to insert the sensor into thehost; and a trigger configured, in response to being activated, to causethe sensor insertion mechanism to insert the sensor into the host, tosecure the electronics unit to the housing such that the sensorelectrically contacts the electronics unit, and to cause the housing todetach from the base.

In an embodiment of the first aspect, which is generally applicable,particularly with any other embodiment of the first aspect, theelectronics unit is configured, in response to the trigger beingactivated and/or the electrical connection of the sensor to theelectronics unit, to generate analyte information. In some embodiments,the electronics unit is configured to transmit the generated analyteinformation in response to the generation of analyte information.

In an embodiment of the first aspect, which is generally applicable,particularly with any other embodiment of the first aspect, the housingcomprises an adhesive configured to attach the housing to the host. Insome embodiments, the adhesive is covered by a liner and/or the adhesiveis air permeable and waterproof or water resistant, and/or the adhesivehas a backing, and the sensor is configured, when inserted into thehost, to extend through the adhesive and backing, and wherein thebacking is configured to be moisture permeable at a location proximal tothe sensor, and/or the adhesive has a backing that is moistureimpermeable in an area peripheral to the housing and the electronicsunit.

In an embodiment of the first aspect, which is generally applicable,particularly with any other embodiment of the first aspect, the housingis configured such that the electronics unit cannot be removed from thehousing while the housing is adhered to the skin of the host.

In an embodiment of the first aspect, which is generally applicable,particularly with any other embodiment of the first aspect, wherein thesensor insertion mechanism comprises a needle configured to be insertedinto the host while the needle holds the sensor, and to be retractedfrom the host while leaving a portion of the sensor in the host. Incertain embodiments, the sensor insertion mechanism further comprises: aneedle hub connected to the needle; a wheel configured to move theneedle hub; and a torsion spring configured to apply a torque to thewheel; wherein the sensor mechanism is configured, in response to theactivation of the trigger, to rotate the wheel in response to the torquefrom the torsion spring, whereby the needle is inserted into the hostand retracted from the host. In certain embodiments, the sensorinsertion mechanism further comprises a push rod configured to preventthe sensor from being retracted from the host with the needle. Incertain embodiments, the push rod is positioned at least partiallywithin the needle, and is configured to move with the needle as theneedle is inserted into the host, and to remain fixed as the needle isretracted from the host.

In an embodiment of the first aspect, which is generally applicable,particularly with any other embodiment of the first aspect, the base isconfigured to draw the electronics unit into the housing. In certainembodiments, the device can further comprise a magnet configured to drawthe electronics unit into the housing, wherein the magnet is situated inthe electronics unit or the housing. In certain embodiments, the basecan comprise one or more springs configured to draw the electronics unitinto the housing. In certain embodiments, each spring can comprise aflexible linear portion having a connection protrusion, wherein theconnection protrusion is configured to engage the electronics unit andto cause the linear portion to flex as the electronics unit is insertedinto the base, and wherein the connection protrusion is configured toexert a lateral force on the electronics unit to draw the electronicsunit into the housing.

In an embodiment of the first aspect, which is generally applicable,particularly with any other embodiment of the first aspect, the devicefurther comprises a standoff configured to limit an extent to which theelectronics unit is inserted into the housing prior to sensor insertion.In certain embodiments the trigger is further configured, in response tobeing activated, to release the electronics unit from the standoff aftersensor insertion, and wherein the electronics unit is configured, inresponse to being released from the standoff, to be secured to thehousing such that the sensor electrically connects to one or morecontacts on the electronics unit. In certain embodiments, in use, a timebetween sensor insertion into the host and the electronics unit securingto the housing is less than about 1 second. In certain embodiments, atleast one contact on the electronics unit is more rigid than the sensor,and wherein the electronics unit is configured such that, when fullysecured to the housing, the at least one contact presses the sensor intoan elastomeric seal such that the elastomeric seal is compressed andconforms to the sensor. In certain embodiments, the sensor, wheninserted into the host, is configured to be secured in place in theelectronics unit by an adhesive material comprising at least one of ahigh tack gel, a pressure sensitive adhesive, and a two part adhesive.In certain embodiments, the device further comprises a containerconfigured to hold the adhesive material, wherein the container isfurther configured, as a result of the trigger activation but before theelectronics unit is released from a lock, to be compressed so as torelease the adhesive material. In certain embodiments, the sensor isconfigured to be secured in place, after insertion into the host, by oneor more of a clamp, a wedge, a barb, a one way valve, or a tension lock.In certain embodiments, the sensor is configured, after insertion intothe host, to be surrounded by an elastomeric seal, and wherein theelectronics unit is configured, in response to the electronics unitbeing released from a lock, to compress the elastomeric seal to securethe sensor and to form a seal around the sensor. In certain embodiments,the sensor is configured, after insertion into the host, to be securedin place by a first group of one or more elastomeric seals configured topress against the sensor with a first force and a second group of one ormore elastomeric seals configured to press against the sensor with asecond force, wherein the first and second forces have differentmagnitudes or different directions. In certain embodiments, at least oneof the first and second groups of elastomeric seals is configured to becompressed while the sensor is inserted through the seals. In certainembodiments, the sensor and needle are configured, after the electronicsunit is secured to the housing, to have a mechanical blockagetherebetween. In certain embodiments, the sensor is configured, afterthe electronics unit is secured to the housing, to be sealed and securedby a ferrule surrounding the sensor. In certain embodiments, the deviceis configured to disengage from the housing and from the electronicsunit in response to the electronics unit being released from a lock. Incertain embodiments, the device is configured to provide one or moretactile, auditory, or visual indications that the electronics unit hasbeen inserted into the housing to the extent permitted by a lock. Incertain embodiments, the device can further comprise an opening throughwhich a mark on the electronics unit is visible if the electronics unithas been inserted into the housing to the extent permitted by thestandoff. In certain embodiments, the device can further comprise adrawing mechanism, wherein a position of the drawing mechanism isconfigured to visually indicate whether the electronics unit has beeninserted into the housing to the extent permitted by the standoff.

In an embodiment of the first aspect, which is generally applicable,particularly with any other embodiment of the first aspect, the devicecan further comprise a trigger lock configured to prevent activation ofthe trigger. In certain embodiments, the trigger is configured to bereleased from the trigger lock in response to at least partial insertionof the electronics unit into the device.

In an embodiment of the first aspect, which is generally applicable,particularly with any other embodiment of the first aspect, the housingis configured to substantially fully encapsulate the electronics unitagainst the host. In certain embodiments, the housing is configured toform a shell that encloses a drawing mechanism, and wherein the housingcomprises a septum through which the sensor insertion mechanism isconfigured to insert the sensor.

In an embodiment of the first aspect, which is generally applicable,particularly with any other embodiment of the first aspect, the sensorinsertion mechanism is configured to insert the sensor into the host ata maximum velocity influenced by a flywheel.

In an embodiment of the first aspect, which is generally applicable,particularly with any other embodiment of the first aspect, the sensorinsertion mechanism is configured to insert the sensor into the host ata maximum velocity influenced by a fluid passage aperture.

In an embodiment of the first aspect, which is generally applicable,particularly with any other embodiment of the first aspect, the sensorinsertion mechanism is configured to insert the sensor into the host ata maximum velocity influenced by a mass of a component of the sensorinsertion mechanism.

In an embodiment of the first aspect, which is generally applicable,particularly with any other embodiment of the first aspect, the sensorinsertion mechanism is configured to insert the sensor into the host ata maximum velocity influenced by a centrifugal brake.

In an embodiment of the first aspect, which is generally applicable,particularly with any other embodiment of the first aspect, the triggeris configured to cause the sensor insertion mechanism to insert thesensor into the host, to secure the electronics unit to the housing suchthat the sensor electrically contacts the electronics unit, and to causethe housing to detach from the base, when motion is provided to thetrigger by a user. In certain embodiments the sensor insertion mechanismcomprises a needle carrier configured to decelerate at a rate limited bya bumper. In certain embodiments, the sensor insertion mechanismcomprises a tab protruding in an axial direction from a wheel andconfigured to rotate about a fixed point, wherein rotational movement ofthe tab translates into a linear movement of a needle carrier to insertthe sensor into the host.

In an embodiment of the first aspect, which is generally applicable,particularly with any other embodiment of the first aspect, the devicecan have a size and shape so as to substantially fit within a palm of ahand.

In an embodiment of the first aspect, which is generally applicable,particularly with any other embodiment of the first aspect, the base issubstantially oval and extends substantially perpendicularly from asubstantially oval shaped wall, and wherein the wall surrounds a topportion on which the trigger is disposed. In certain embodiments, thetrigger forms substantially an entire top of the device.

In an embodiment of the first aspect, which is generally applicable,particularly with any other embodiment of the first aspect, the devicefurther comprises a protective cover configured to cover the electronicsunit and the housing after sensor insertion and to secure theelectronics unit to the housing. In some embodiments, an internalportion of the protective cover conforms to the shape of the base andthe electronics unit. In some embodiments, the protective cover iswaterproof or water resistant, and is air permeable. In someembodiments, the protective cover is molded to have an appearance of ananimal or a character. In some embodiments, the protective covercomprises an adhesive that attaches the protective cover to the housingand/or electronics unit.

In an embodiment of the first aspect, which is generally applicable,particularly with any other embodiment of the first aspect, the devicehas an exterior formed at least partly of a hard plastic.

In an embodiment of the first aspect, which is generally applicable,particularly with any other embodiment of the first aspect, the devicefurther comprises an elastomer, wherein the elastomer is situated atleast partly around a perimeter of the device and is configured torelieve strain caused by movement of the host.

In an embodiment of the first aspect, which is generally applicable,particularly with any other embodiment of the first aspect, theelectronics unit is configured, once it is secured to the housing, todestroy the housing upon removal from the housing.

In an embodiment of the first aspect, which is generally applicable,particularly with any other embodiment of the first aspect, the devicefurther comprises a blood reservoir configured to receive blood from thehost through a weep hole in the housing. In some embodiments, thereservoir comprises at least one of a sponge, a super absorbent polymer,or a wicking material configured to absorb the blood. In someembodiments, the reservoir is an aerated reservoir.

In an embodiment of the first aspect, which is generally applicable,particularly with any other embodiment of the first aspect, theelectronics unit comprises at least one electrical contact comprisingone or more conductive materials selected from carbon, a carbon embeddedsilicone elastomer, a conductive polymer, or a conductive salt.

In an embodiment of the first aspect, which is generally applicable,particularly with any other embodiment of the first aspect, the sensorcomprises an electrical contact comprising one or more conductivematerials selected from carbon, a carbon embedded silicone elastomer, aconductive polymer, or a conductive salt.

In a second aspect, a method is provided of applying an on-skin sensorassembly to a host, wherein the on-skin sensor assembly comprises ahousing secured to the applicator, wherein the housing is configured toreceive an electronics unit, the method comprising: attaching anapplicator to a skin of a host, the applicator comprising a sensorinsertion mechanism, a trigger, and a base; inserting the electronicsunit into the housing, wherein the electronics unit is configured togenerate analyte information based on a signal from a sensor; activatingthe trigger, thereby causing the sensor insertion mechanism to insert asensor into the host, to secure the electronics unit to the housing suchthat the sensor electrically contacts the electronics unit, and to causethe housing to detach from the base; and removing the applicator fromthe skin of the host, whereby an on-skin sensor assembly comprising thehousing, the electronics unit, and the inserted sensor remains on theskin of the host.

In an embodiment of the second aspect, which is generally applicable,particularly with any other embodiment of the second aspect, attachingthe applicator to the skin of the host occurs before the electronicsunit is inserted into the housing.

In an embodiment of the second aspect, which is generally applicable,particularly with any other embodiment of the second aspect, attachingthe applicator to the skin of the host occurs after the electronics unitis inserted into the housing.

In an embodiment of the second aspect, which is generally applicable,particularly with any other embodiment of the second aspect, the methodfurther comprises before applying the applicator, removing a door fromthe applicator covering a port configured for receiving the electronicsunit when the electronics unit is inserted into the housing.

In an embodiment of the second aspect, which is generally applicable,particularly with any other embodiment of the second aspect, the methodfurther comprises a removable liner covering an adhesive patch, whereinthe adhesive patch is attached to the housing and radially extends fromthe housing, and wherein the adhesive patch comprises an adhesiveconfigured to attach the base to the host. In certain embodiments, theadhesive patch is removably attached to the base with a second adhesivethat is weaker than the adhesive configured to attach the base to thehost, and/or the adhesive patch comprises a removable second linersituated between the base and the adhesive patch. In certainembodiments, the second liner is removably attached to the base with asecond adhesive. In certain embodiments, the device is provided in apackage configured to contain the base, the housing, the sensorinsertion mechanism, and the trigger, wherein the package comprises theremovable liner covering the adhesive patch. In certain embodiments, thepackage further comprises a cover, wherein the cover is a component ofthe applicator. In certain embodiments, the package further comprises aremovable door, wherein the removable door covers a port configured forreceiving the electronics unit. In certain embodiments, the removableliner comprises instructions printed thereon for using the applicator.In certain embodiments, multiple applicators are provided in thepackage.

In an embodiment of the second aspect, which is generally applicable,particularly with any other embodiment of the second aspect, theapplicator comprises a removable liner covering an adhesive patch,wherein the adhesive patch is attached to the housing, wherein theadhesive patch comprises an adhesive configured to attach the base tothe host, wherein removing the applicator from the package exposes theadhesive, and wherein attaching the applicator causes the adhesive toattach the housing to the host.

In a third aspect, a method is provided of applying an on-skin sensorassembly to a host, the method comprising: attaching an applicator to askin of a host, the applicator comprising a sensor insertion mechanism,a trigger, and a base; a housing secured to the applicator, wherein thehousing is configured to receive an electronics unit; activating thetrigger, thereby causing the sensor insertion mechanism to insert asensor into the host and to cause the housing to detach from the base;removing the applicator from the skin of the host, whereby the housingand the inserted sensor remain on the skin of the host; and insertingthe electronics unit into the housing, wherein the electronics unit isconfigured to generate analyte information based on a signal from thesensor, and wherein the electronics unit is secured to the housing suchthat the sensor electrically contacts the electronics unit, whereby anon-skin sensor assembly comprising the housing, the electronics unit,and the inserted sensor is obtained.

In an embodiment of the third aspect, which is generally applicable,particularly with any other embodiment of the third aspect, the housingis configured to receive the electronics unit in a partially seatedconfiguration, and wherein the trigger is configured, in response tobeing activated, to cause the sensor insertion mechanism to insert thesensor into the host and to fully seat the electronics unit to thehousing such that the sensor electrically contacts the electronics unit.In certain embodiments, the partially seated configuration is providedby a lock configured to limit an extent to which the electronics unitcan be inserted into the housing prior to sensor insertion. In certainembodiments, the trigger is further configured to release theelectronics unit from the lock after sensor insertion, wherein inresponse to the electronics unit being released from the lock, theelectronics unit is configured to be secured to the housing such thatthe sensor electrically connects to one or more contacts on theelectronics unit. In certain embodiments, a time between the sensorinsertion into the host and the electronics unit securing the sensor isless than about 1 s.

In an embodiment of the third aspect, which is generally applicable,particularly with any other embodiment of the third aspect, the base isconfigured to draw the electronics unit into the housing. In certainembodiments, at least one of the electronics unit and the housingcomprises a magnet configured to draw the electronics unit into thehousing. In certain embodiments, the base comprises one or more springsconfigured to draw the electronics unit into the housing. In certainembodiments, each spring is connected to a contact element, wherein thecontact element is configured to engage the electronics unit and tocause the spring to compress as the electronics unit is inserted intothe housing, and wherein the contact element is configured to exert alateral force on the electronics unit to draw the electronics unit intothe housing. In certain embodiments, each spring comprises a flexiblelinear portion having a connection protrusion, wherein the connectionprotrusion is configured to engage the electronics unit and to cause thelinear portion to flex as the electronics unit is inserted into thebase, and wherein the connection protrusion is configured to exert alateral force on the electronics unit to draw the electronics unit intothe housing.

In an embodiment of the third aspect, which is generally applicable,particularly with any other embodiment of the third aspect, the deviceis configured to provide one or more tactile, auditory, or visualindications that the electronics unit has been inserted into the housingin the partially seated configuration.

In an embodiment of the third aspect, which is generally applicable,particularly with any other embodiment of the third aspect, the devicefurther comprises a trigger lock configured to prevent activation of thetrigger. In certain embodiments, the trigger is configured to bereleased from the trigger lock in response to at least partial insertionof the electronics unit into the housing.

In an embodiment of the third aspect, which is generally applicable,particularly with any other embodiment of the third aspect, the housingis configured to adhere to a host's skin, wherein, in use, the sensor isconfigured to extend through the housing and into the host's skin; andthe electronics unit is configured to operably connect to the sensor andgenerate analyte information based on a signal from the sensor when theelectronics unit is secured within the housing, wherein operableconnection of the electronics unit to the sensor comprises pressing thesensor against one or more electrical contacts of the electronics unit,and wherein the sensor is configured to be held in the assembly with aretention force.

In an embodiment of the third aspect, which is generally applicable,particularly with any other embodiment of the third aspect, the sensoris configured such that connection of the electronics unit to the sensorcauses the sensor to bend, whereby the sensor is configured to conformto the shape of the one or more electrical contacts.

In an embodiment of the third aspect, which is generally applicable,particularly with any other embodiment of the third aspect, the sensoris configured to be secured in place after insertion in the host by anadhesive material comprising at least one of a high tack gel, a pressuresensitive adhesive, or a two part adhesive. In certain embodiments, theadhesive material is configured to be enclosed in the container, andwherein the container is configured to be compressed so as to releasethe adhesive material upon activation of the trigger.

In an embodiment of the third aspect, which is generally applicable,particularly with any other embodiment of the third aspect, the sensoris configured to be secured in place by one or more of a clamp, a wedge,a barb, a one way valve, or a tension lock.

In an embodiment of the third aspect, which is generally applicable,particularly with any other embodiment of the third aspect, the housingcomprises an elastomeric seal configured to form a seal around thesensor when the electronics unit is operably connected to the sensor.

In an embodiment of the third aspect, which is generally applicable,particularly with any other embodiment of the third aspect, the sensoris configured, after insertion into the host, to be secured in place bya first group of one or more elastomeric seals configured to pressagainst the sensor with a first force and a second group of one or moreelastomeric seals configured to press against the sensor with a secondforce, wherein the first and second forces have different magnitudesand/or different directions. In certain embodiments, at least one of thefirst and second groups of elastomeric seals is configured to becompressed while the sensor is inserted through the seals.

In an embodiment of the third aspect, which is generally applicable,particularly with any other embodiment of the third aspect, the sensorand needle are configured, after the electronics unit is secured to thehousing, to have a mechanical blockage therebetween.

In an embodiment of the third aspect, which is generally applicable,particularly with any other embodiment of the third aspect, the sensoris configured, after the electronics unit is secured to the housing, tobe sealed and secured by a ferrule surrounding the sensor.

In an embodiment of the third aspect, which is generally applicable,particularly with any other embodiment of the third aspect, the sensoris in a form of a wire.

In an embodiment of the third aspect, which is generally applicable,particularly with any other embodiment of the third aspect, theretention force is at least about 0.1 pounds when subjected to astandard pull test or a standard push test.

In an embodiment of the third aspect, which is generally applicable,particularly with any other embodiment of the third aspect, theelectronics unit is inserted into the housing after the applicator isremoved from the skin of the host.

In a fourth aspect, a device is provided for applying an on-skin sensorassembly to skin of a host, the device comprising: a base configured tosecure a housing, wherein the housing is configured to receive atransmitter, and the transmitter is configured to generate analyteinformation based on a signal from a sensor; and a mechanism configuredto, in response to a single action by a user, cause the sensor to beinserted into the host, to secure the electronics unit to the housingsuch that the sensor electrically contacts the electronics unit, and tocause the housing to detach from the base.

In an embodiment of the fourth aspect, which is generally applicable,particularly with any other embodiment of the fourth aspect, themechanism includes a trigger, and the single action comprises activatingthe trigger to release stored energy and set components within thedevice in motion. In certain embodiments, the stored energy is stored ina torsion spring that, when released, causes a wheel to rotate. Incertain embodiments, rotation of the wheel induces linear motion in aneedle carrier. In certain embodiments, the wheel and the needle carriercomprise a Scotch yoke.

In an embodiment of the fourth aspect, which is generally applicable,particularly with any other embodiment of the fourth aspect, themechanism further includes a pushrod and a needle, and when themechanism is activated the pushrod ejects the sensor from a lumen of theneedle and subsequently retracts into the needle lumen.

In an embodiment of the fourth aspect, which is generally applicable,particularly with any other embodiment of the fourth aspect, themechanism is prevented from actuation until the transmitter is partiallyseated within the housing.

In a fifth aspect, a device is provided for applying an on-skin sensorassembly to skin of a host, the device comprising: a sensor; a sensorinsertion mechanism containing the sensor; and a housing containing thesensor insertion mechanism, the housing being substantially dome shapedsuch that it is configured to be comfortably held in the palm of a hand,and such that the housing can be held during a process of inserting thesensor into the skin of the host at any location on the abdomen of thehost with the host's wrist in a neutral position.

In a sixth aspect, a device is provided for applying an on-skin sensorassembly to skin of a host, the device comprising: a base configured tosecure a housing, wherein the housing is configured to receive anelectronics unit, wherein the electronics unit is configured to generateanalyte information based on a signal from a sensor; a sensor insertionmechanism configured to insert the sensor into the host, and including aneedle carrying the sensor, a rotatable wheel, and a linearlytranslatable needle carrier; and a trigger configured, in response tobeing activated, to cause the rotatable wheel to rotate, which in turncauses the linearly translatable needle carrier to translate toward thehost to implant the sensor, and subsequently to translate away from thehost to withdraw the needle from the host.

In an embodiment of the sixth aspect, which is generally applicable,particularly with any other embodiment of sixth aspect, the wheel andthe needle carrier comprise a Scotch yoke.

In an embodiment of the sixth aspect, which is generally applicable,particularly with any other embodiment of sixth aspect, the devicefurther comprises a torsion spring that stores energy, and when thetrigger is activated, the energy stored in the torsion spring isreleased, causing the wheel to rotate. In some embodiments, the wheelincludes a flange, and the trigger bears against the flange to retainthe energy stored within the torsion spring.

In an embodiment of the sixth aspect, which is generally applicable,particularly with any other embodiment of sixth aspect, the devicefurther comprises a pushrod and a needle, and when the trigger isactivated the pushrod ejects the sensor from a lumen of the needle andsubsequently retracts into the needle lumen.

In an embodiment of the sixth aspect, which is generally applicable,particularly with any other embodiment of sixth aspect, the trigger isprevented from actuation until the electronics unit is partially seatedwithin the housing.

In a seventh aspect, a device is provided for applying an on-skin sensorassembly to skin of a host, the device comprising: a base configured tosecure a housing; and an electronics unit including at least oneelectrical contact, wherein the housing is configured to receive theelectronics unit, wherein the electronics unit is configured to generateanalyte information based on a signal from a sensor; wherein the baseincludes a mechanism to apply a seating force to the electronics unit ina direction of insertion of the electronics unit into the housing uponpartial seating of the electronics unit within the housing.

In an embodiment of the seventh aspect, which is generally applicable,particularly with any other embodiment of seventh aspect, the seatingforce is about 0.25-3 lbs.

In an embodiment of the seventh aspect, which is generally applicable,particularly with any other embodiment of seventh aspect, uponactivation of the device, a sealing force is applied to the sensor thatis about 2-3 times the magnitude of the seating force.

In an embodiment of the seventh aspect, which is generally applicable,particularly with any other embodiment of seventh aspect, the mechanismincludes a pair of spring arms, and the spring arms are pre-loaded withstored energy, and partially seating the electronics unit within thehousing releases the stored energy.

In an embodiment of the seventh aspect, which is generally applicable,particularly with any other embodiment of seventh aspect, the mechanismincludes a pair of spring arms, and the spring arms are pre-loaded withstored energy, and activating the device releases the stored energy.

In an embodiment of the seventh aspect, which is generally applicable,particularly with any other embodiment of seventh aspect, uponactivation of the device the force moves the electronics unit fartherinto the housing, causing the at least one electrical contact to contactthe sensor.

In an embodiment of the seventh aspect, which is generally applicable,particularly with any other embodiment of seventh aspect, the mechanismcomprises at least one spring. In certain embodiments, the at least onespring is a leaf spring. In certain embodiments, the at least one springis a pair of leaf springs located on opposite sides of the electronicsunit.

In an embodiment of the seventh aspect, which is generally applicable,particularly with any other embodiment of seventh aspect, partialseating of the electronics unit releases a trigger lock, therebyallowing the device to be actuated. In certain embodiments, if theelectronics unit backs out from the partially seated position, thetrigger lock reengages, thereby preventing the device from beingactuated.

In an eighth aspect, a device is provided for applying an on-skin sensorassembly to skin of a host, the device comprising: a housing; and anelectronics unit, wherein the electronics unit is configured to generateanalyte information based on a signal from a sensor; a sensor insertionmechanism configured to insert the sensor into the host; and a triggerconfigured, in response to being activated, to cause the sensorinsertion mechanism to insert the sensor into skin of the host, and tosecure the electronics unit to the housing such that the sensorelectrically contacts the electronics unit, and in such a way that reuseof the sensor is prevented.

In an embodiment of the eighth aspect, which is generally applicable,particularly with any other embodiment of eighth aspect, the electronicsunit may not be removed from the housing without destroying the housing.

In an embodiment of the eighth aspect, which is generally applicable,particularly with any other embodiment of eighth aspect, the electronicsunit may not be removed from the housing without removing an adhesivepatch located between the housing and the host from the housing or fromthe host.

In an embodiment of the eighth aspect, which is generally applicable,particularly with any other embodiment of eighth aspect, when thehousing is adhered to the host's skin, the skin blocks movement of alever, which is used to remove the transmitter from the housing suchthat the transmitter can only be removed from the housing after thesensor has been removed from the body and is thereby rendered unusable.

In a ninth aspect, a device is provided for applying an on-skin sensorassembly to skin of a host, the device comprising: a housing, whereinthe housing is configured to receive an electronics unit, wherein theelectronics unit is configured to generate analyte information based ona signal from a sensor; a sensor insertion mechanism configured toinsert the sensor into the host; a trigger configured, in response tobeing activated, to cause the sensor insertion mechanism to insert thesensor into the host; and a trigger lock configured to preventactivation of the trigger until the electronics unit is partially seatedwithin the housing.

In an embodiment of the ninth aspect, which is generally applicable,particularly with any other embodiment of ninth aspect, the trigger lockcomprises a projection on a rear side of the trigger that engages asurface to prevent movement of the trigger.

In an embodiment of the ninth aspect, which is generally applicable,particularly with any other embodiment of ninth aspect, if theelectronics unit backs out from the partially seated position, thetrigger lock reengages, thereby preventing the device from beingactuated.

In an embodiment of the ninth aspect, which is generally applicable,particularly with any other embodiment of ninth aspect, the electronicsunit disengages the trigger lock as it is partially seated within thehousing.

In further aspects and embodiments, the above method features of thevarious aspects are formulated in terms of a system as in variousaspects, having the analyte sensor and control means configured to carryout the method features. Any of the features of an embodiment of any ofthe aspects, including but not limited to any embodiments of any of thefirst through ninth aspects referred to above, is applicable to allother aspects and embodiments identified herein, including but notlimited to any embodiments of any of the first through ninth aspectsreferred to above. Moreover, any of the features of an embodiment of thevarious aspects, including but not limited to any embodiments of any ofthe first through ninth aspects referred to above, is independentlycombinable, partly or wholly with other embodiments described herein inany way, e.g., one, two, or three or more embodiments may be combinablein whole or in part. Further, any of the features of an embodiment ofthe various aspects, including but not limited to any embodiments of anyof the first through ninth aspects referred to above, may be madeoptional to other aspects or embodiments. Any aspect or embodiment of amethod can be performed by a system or apparatus of another aspect orembodiment, and any aspect or embodiment of a system or apparatus can beconfigured to perform a method of another aspect or embodiment,including but not limited to any embodiments of any of the first throughninth aspects referred to above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a continuous analyte sensor systemattached to a host and communicating with other devices;

FIGS. 2A-2D are front perspective views of a sensor system andapplicator at various stages of a process for applying the sensor systemto a host;

FIG. 3A is an exploded view of the sensor system and applicator of FIGS.2A-2D;

FIG. 3B is an exploded view of a generally applicable embodiment of asensor system and applicator;

FIG. 3C is an assembled front perspective view of the sensor system andapplicator of FIG. 3B;

FIG. 4 is a side cross-sectional view of the applicator of FIG. 3A;

FIGS. 5A-5C are rear perspective views of select components of theapplicator of FIG. 3B, showing a process for inserting the sensor systeminto the applicator;

FIGS. 5D and 5E are rear cross-sectional perspective views of theapplicator of FIG. 3A during insertion of the transmitter;

FIGS. 6A-6D are front perspective views of selected components of theapplicator of FIG. 3B, showing a process for inserting the sensor intothe host;

FIG. 7 is a front perspective view of components of the sensor system ofFIG. 3B, including the transmitter;

FIGS. 8A and 8B are front perspective cross-sectional views of portionsof the applicator and sensor system of FIG. 3A at different stages in amethod of applying the sensor system to the host, showing a mechanismfor connecting the sensor to contacts on a transmitter of the sensorsystem during seating of the transmitter;

FIGS. 9A-9E are front perspective cross-sectional views of theapplicator and sensor system of FIG. 3B at various stages in a method ofapplying the sensor system, showing actuation of a needle carrying thesensor and engagement of a proximal end of the sensor with contacts on atransmitter of the sensor system;

FIG. 9F is a rear perspective cross-sectional view of the applicator ofFIG. 3A with the transmitter seated;

FIG. 10 is a front perspective view of the sensor system of FIG. 5Aafter application to the host;

FIGS. 11A and 11B are exploded views of generally applicable embodimentsof an applicator;

FIGS. 12A-12D are perspective/plan views of generally applicableembodiments of a housing;

FIGS. 13A-13D are perspective views of a generally applicable embodimentof a housing;

FIG. 14 is a lower plan view of a generally applicable embodiment of ahousing;

FIG. 15 is a front perspective view of a needle carrier for use in anapplicator;

FIGS. 16A-16D are side elevation views showing use of the needle carrierof FIG. 15;

FIGS. 17A and 17B are cross-sectional side views of a generallyapplicable embodiment of an applicator showing a latching mechanism forthe needle carrier;

FIG. 18 is a cross-sectional side view of a generally applicableembodiment of an applicator showing a latch design;

FIGS. 19A and 19B are rear perspective views of a generally applicableembodiment of an applicator and sensor system, illustrating a processfor inserting the sensor system into the applicator;

FIGS. 20A-20C are cross-sectional views of a mechanism for drawing atransmitter into a housing;

FIGS. 21A-21C are side perspective views of a generally applicableembodiment of a latch for an applicator;

FIGS. 22A-22C are side perspective views of generally applicableembodiments of mechanisms for reducing play in the needle carrier ofFIG. 24;

FIGS. 23A and 23B are front perspective views of a generally applicableembodiment of a sensor insertion mechanism;

FIGS. 24A-24C are front perspective views showing actuation of themechanism of FIGS. 23A and 23B;

FIG. 25A is a side elevation view of a generally applicable embodimentof a pushrod;

FIG. 25B is a front perspective view showing attachment of the pushrodof FIG. 25A to the mechanism of FIGS. 23A and 23B;

FIG. 26 is a front perspective view showing a generally applicableembodiment of an applicator;

FIGS. 27A-27D are schematic cross-sectional views of the applicator ofFIG. 26, illustrating a method of using the applicator to apply a sensorsystem to a host;

FIGS. 28A and 28B are cross-sectional side views of a generallyapplicable embodiment of an applicator;

FIGS. 29A and 29B are front perspective views of an applicator in apackage and a sensor system for use with the applicator;

FIGS. 30A-30D are rear perspective views of various generally applicableembodiments of housings having capillary channels; and

FIG. 31A is a side elevation view of a generally applicable embodimentof an applicator having sensors to detect that the applicator has beenplaced on the host;

FIG. 31B is a bottom plan view of the applicator of FIG. 31A;

FIG. 31C is a side elevation view of a generally applicable embodimentof an applicator having sensors to detect that the applicator has beenplaced on the host;

FIG. 31D is a bottom plan view of the applicator of FIG. 31C;

FIGS. 32-35 are schematic views of an in-situ renewable adhesive patch,according to a generally applicable embodiment;

FIGS. 36-38 are schematic views of a moisture sensitive compressionincreasing seal, according to a generally applicable embodiment;

FIG. 39 is a schematic view of a rounded kink feature for sensorretention, according to a generally applicable embodiment;

FIG. 40 is a schematic view of a S-bend kink feature for sensorretention, according to a generally applicable embodiment;

FIG. 41 is a schematic view of a triple-bump kink feature for sensorretention, according to a generally applicable embodiment;

FIGS. 42-44 are schematic views of a process for making a seamlesscleanable transmitter, according to a generally applicable embodiment;

FIG. 45 is a lower perspective view of a housing, according to agenerally applicable embodiment;

FIG. 46 is a schematic view of a sensor pod adhesive design, accordingto a generally applicable embodiment;

FIG. 47 is a rear perspective view of a housing, according to agenerally applicable embodiment; and

FIGS. 48-51 are various perspective and elevation views of atransmitter, according to a generally applicable embodiment.

DETAILED DESCRIPTION

The following description and examples illustrate some exampleembodiments of the disclosed invention in detail. Those of skill in theart will recognize that there are numerous variations and modificationsof this invention that are encompassed by its scope. Accordingly, thedescription of a certain example embodiment should not be deemed tolimit the scope of the present invention.

Sensor System and Applicator

FIG. 1 is a schematic of a continuous analyte sensor system 100 attachedto a host and communicating with a number of other example devices110-113. A transcutaneous analyte sensor system comprising an on-skinsensor assembly 600 is shown which is fastened to the skin of a host viaa disposable housing (not shown). The system includes a transcutaneousanalyte sensor 200 and an electronics unit (referred to interchangeablyas “sensor electronics” or “transmitter”) 500 for wirelesslytransmitting analyte information to a receiver. During use, a sensingportion of the sensor 200 is under the host's skin and a contact portionof the sensor 200 is electrically connected to the electronics unit 500.The electronics unit 500 is engaged with a housing which is attached toan adhesive patch fastened to the skin of the host.

The on-skin sensor assembly 600 may be attached to the host with use ofan applicator adapted to provide convenient and secure application. Suchan applicator may also be used for attaching the electronics unit 500 toa housing, inserting the sensor 200 through the host's skin, andconnecting the sensor 200 to the electronics unit 500. Once theelectronics unit 500 is engaged with the housing and the sensor 200 hasbeen inserted and is connected to the electronics unit 500, theapplicator detaches from the sensor assembly.

In general, the continuous analyte sensor system 100 includes any sensorconfiguration that provides an output signal indicative of aconcentration of an analyte. The output signal including (e.g., sensordata, such as a raw data stream, filtered data, smoothed data, and/orotherwise transformed sensor data) is sent to the receiver, which isdescribed in more detail below. In one embodiment, the analyte sensorsystem 100 includes a transcutaneous glucose sensor, such as isdescribed in US Patent Publication No. US-2011-0027127-A1, the contentsof which is hereby incorporated by reference in its entirety. In someembodiments, the sensor system 100 includes a continuous glucose sensorand comprises a transcutaneous sensor such as described in U.S. Pat. No.6,565,509 to Say et al., for example. In another embodiment, the sensorsystem 100 includes a continuous glucose sensor and comprises asubcutaneous sensor such as described with reference to U.S. Pat. No.6,579,690 to Bonnecaze et al. or U.S. Pat. No. 6,484,046 to Say et al.,for example. In another embodiment, the sensor system 100 includes acontinuous glucose sensor and comprises a refillable subcutaneous sensorsuch as described with reference to U.S. Pat. No. 6,512,939 to Colvin etal. In another embodiment, the sensor system 100 includes a continuousglucose sensor and comprises an intravascular sensor such as describedwith reference to U.S. Pat. No. 6,477,395 to Schulman et al., forexample. In another embodiment, the sensor system 100 includes acontinuous glucose sensor and comprises an intravascular sensor such asdescribed with reference to U.S. Pat. No. 6,424,847 to Mastrototaro etal. Other signal processing techniques and glucose monitoring systemembodiments suitable for use with the embodiments described herein aredescribed in U.S. Patent Publication No. US-2005-0203360-A1 and U.S.Patent Publication No. US-2009-0192745-A1, the contents of which arehereby incorporated by reference in their entirety. The sensor extendsthrough a housing, which maintains the sensor on the skin and providesfor electrical connection of the sensor to sensor electronics, providedin the electronics unit.

In one embodiment, the sensor is formed from a wire or is in a form of awire. For example, the sensor can include an elongated conductive body,such as, a bare elongated conductive core (e.g., a metal wire) or anelongated conductive core coated with one, two, three, four, five, ormore layers of material, each of which may or may not be conductive. Theelongated sensor may be long and thin, yet flexible and strong. Forexample, in some embodiments, the smallest dimension of the elongatedconductive body is less than about 0.1 inches, less than about 0.075inches, less than about 0.05 inches, less than about 0.025 inches, lessthan about 0.01 inches, less than about 0.004 inches, or less than about0.002 inches. The sensor may have a circular cross-section. In someembodiments, the cross-section of the elongated conductive body can beovoid, rectangular, triangular, polyhedral, star-shaped, C-shaped,T-shaped, X-shaped, Y-Shaped, irregular, or the like. In one embodiment,a conductive wire electrode is employed as a core. To such a cladelectrode, one or two additional conducting layers may be added (e.g.,with intervening insulating layers provided for electrical isolation).The conductive layers can be comprised of any suitable material. Incertain embodiments, it can be desirable to employ a conductive layercomprising conductive particles (i.e., particles of a conductivematerial) in a polymer or other binder.

In certain embodiments, the materials used to form the elongatedconductive body (e.g., stainless steel, titanium, tantalum, platinum,platinum-iridium, iridium, certain polymers, and/or the like) can bestrong and hard, and therefore are resistant to breakage. For example,in some embodiments, the ultimate tensile strength of the elongatedconductive body is from about 80 kPsi to about 500 kPsi. In anotherexample, in some embodiments, the Young's modulus of the elongatedconductive body is from about 160 GPa to about 220 GPa. In still anotherexample, in some embodiments, the yield strength of the elongatedconductive body is from about 60 kPsi to about 2200 kPsi. Ultimatetensile strength, Young's modulus, and yield strength are discussed ingreater detail elsewhere herein. In some embodiments, the sensor's smalldiameter provides (e.g., imparts, enables) flexibility to thesematerials, and therefore to the sensor as a whole. Thus, the sensor canwithstand repeated forces applied to it by surrounding tissue. Onemeasurement of the sensor's ability to withstand the implantationenvironment is fatigue life, which is described in greater detail in thesection entitled “Multi-Axis Bending.” In some embodiments, the fatiguelife of the sensor is at least 1,000 cycles of flexing of from about 28°to about 110° at a bend radius of about 0.125-inches.

In addition to providing structural support, resiliency and flexibility,in some embodiments, the core (or a component thereof) provideselectrical conduction for an electrical signal from the workingelectrode to sensor electronics (not shown), which are describedelsewhere herein. In some embodiments, the core comprises a conductivematerial, such as stainless steel, titanium, tantalum, a conductivepolymer, and/or the like. However, in other embodiments, the core isformed from a non-conductive material, such as a non-conductive polymer.In yet other embodiments, the core comprises a plurality of layers ofmaterials. For example, in one embodiment the core includes an innercore and an outer core. In a further embodiment, the inner core isformed of a first conductive material and the outer core is formed of asecond conductive material. For example, in some embodiments, the firstconductive material is stainless steel, titanium, tantalum, a conductivepolymer, an alloy, and/or the like, and the second conductive materialis conductive material selected to provide electrical conduction betweenthe core and the first layer, and/or to attach the first layer to thecore (e.g., if the first layer is formed of a material that does notattach well to the core material). In another embodiment, the core isformed of a non-conductive material (e.g., a non-conductive metal and/ora non-conductive polymer) and the first layer is a conductive material,such as stainless steel, titanium, tantalum, a conductive polymer,and/or the like. The core and the first layer can be of a single (orsame) material, e.g., platinum. One skilled in the art appreciates thatadditional configurations are possible.

In the illustrated embodiments, the electronics unit 500 is releasablyattachable to the sensor 200. The electronics unit 500 includeselectronic circuitry associated with measuring and processing thecontinuous analyte sensor data, and is configured to perform algorithmsassociated with processing and calibration of the sensor data. Forexample, the electronics unit 500 can provide various aspects of thefunctionality of a sensor electronics module as described in U.S. PatentPublication No. US-2009-0240120-A1 and U.S. patent application Ser. No.13/247,856 filed Sep. 28, 2011 and entitled “ADVANCED CONTINUOUS ANALYTEMONITORING SYSTEM,” the contents of which are hereby incorporated byreference in their entirety. The electronics unit 500 may includehardware, firmware, and/or software that enable measurement of levels ofthe analyte via a glucose sensor, such as an analyte sensor 200. Forexample, the electronics unit 500 can include a potentiostat, a powersource for providing power to the sensor 200, other components usefulfor signal processing and data storage, and preferably a telemetrymodule for one- or two-way data communication between the electronicsunit 500 and one or more receivers, repeaters, and/or display devices,such as devices 110-113. Electronics can be affixed to a printed circuitboard (PCB), or the like, and can take a variety of forms. For example,the electronics can take the form of an integrated circuit (IC), such asan Application-Specific Integrated Circuit (ASIC), a microcontroller,and/or a processor. The electronics unit 500 may include sensorelectronics that are configured to process sensor information, such asstoring data, analyzing data streams, calibrating analyte sensor data,estimating analyte values, comparing estimated analyte values with timecorresponding measured analyte values, analyzing a variation ofestimated analyte values, and the like. Examples of systems and methodsfor processing sensor analyte data are described in more detail hereinand in U.S. Pat. Nos. 7,310,544, 6,931,327, U.S. Patent Publication No.2005-0043598-A1, U.S. Patent Publication No. 2007-0032706-A1, U.S.Patent Publication No. 2007-0016381-A1, U.S. Patent Publication No.2008-0033254-A1, U.S. Patent Publication No. 2005-0203360-A1, U.S.Patent Publication No. 2005-0154271-A1, U.S. Patent Publication No.2005-0192557-A1, U.S. Patent Publication No. 2006-0222566-A1, U.S.Patent Publication No. 2007-0203966-A1 and U.S. Patent Publication No.2007-0208245-A1, the contents of which are hereby incorporated byreference in their entirety.

One or more repeaters, receivers and/or display devices, such as key fobrepeater 110, medical device receiver 111 (e.g., insulin delivery deviceand/or dedicated glucose sensor receiver), smart phone 112, portablecomputer 113, and the like are operatively linked to the electronicsunit, which receive data from the electronics unit 500, which is alsoreferred to as the transmitter and/or sensor electronics body herein,and in some embodiments transmit data to the electronics unit 500. Forexample, the sensor data can be transmitted from the sensor electronicsunit 500 to one or more of key fob repeater 110, medical device receiver111, smart phone 112, portable computer 113, and the like. In oneembodiment, a display device includes an input module with a quartzcrystal operably connected to an RF transceiver (not shown) thattogether function to transmit, receive and synchronize data streams fromthe electronics unit 500. However, the input module can be configured inany manner that is capable of receiving data from the electronics unit500. Once received, the input module sends the data stream to aprocessor that processes the data stream, such as described in moredetail below. The processor is the central control unit that performsthe processing, such as storing data, analyzing data streams,calibrating analyte sensor data, estimating analyte values, comparingestimated analyte values with time corresponding measured analytevalues, analyzing a variation of estimated analyte values, downloadingdata, and controlling the user interface by providing analyte values,prompts, messages, warnings, alarms, and the like. The processorincludes hardware that performs the processing described herein, forexample read-only memory (ROM) provides permanent or semi-permanentstorage of data, storing data such as sensor ID (sensor identity),receiver ID (receiver identity), and programming to process data streams(for example, programming for performing estimation and other algorithmsdescribed elsewhere herein) and random access memory (RAM) stores thesystem's cache memory and is helpful in data processing. An outputmodule, which may be integral with and/or operatively connected with theprocessor, includes programming for generating output based on thesensor data received from the electronics unit (and any processing thatincurred in the processor).

In some embodiments, analyte values are displayed on a display device.In some embodiments, prompts or messages can be displayed on the displaydevice to convey information to the user, such as reference outliervalues, requests for reference analyte values, therapy recommendations,deviation of the measured analyte values from the estimated analytevalues, or the like. Additionally, prompts can be displayed to guide theuser through calibration or trouble-shooting of the calibration.

Additionally, data output from the output module can provide wired orwireless, one- or two-way communication between the receiver and anexternal device. The external device can be any device that interfacesor communicates with the receiver. In some embodiments, the externaldevice is a computer, and the receiver is able to download current orhistorical data for retrospective analysis by a physician, for example.In some embodiments, the external device is a modem, and the receiver isable to send alerts, warnings, emergency messages, or the like, viatelecommunication lines to another party, such as a doctor or familymember. In some embodiments, the external device is an insulin pen, andthe receiver is able to communicate therapy recommendations, such asinsulin amount and time to the insulin pen. In some embodiments, theexternal device is an insulin pump, and the receiver is able tocommunicate therapy recommendations, such as insulin amount and time tothe insulin pump. The external device can include other technology ormedical devices, for example pacemakers, implanted analyte sensorpatches, other infusion devices, telemetry devices, or the like. Thereceiver may communicate with the external device, and/or any number ofadditional devices, via any suitable communication protocol, includingradio frequency, Bluetooth, universal serial bus, any of the wirelesslocal area network (WLAN) communication standards, including the IEEE802.11, 802.15, 802.20, 802.22 and other 802 communication protocols,ZigBee, wireless (e.g., cellular) telecommunication, paging networkcommunication, magnetic induction, satellite data communication, GPRS,ANT, and/or a proprietary communication protocol.

FIGS. 2A-2D are perspective views of the on-skin sensor assembly andapplicator at various stages in a method of an application process in agenerally applicable embodiment.

FIG. 2A shows an embodiment of an applicator 400. The applicator 400 hasa liner 490 connected thereto which covers an adhesive (not shown). FIG.2A also shows an embodiment of an electronics unit, also referred to asa transmitter 500. As indicated, the transmitter 500 is inserted throughan opening 830 (FIG. 29B) in the applicator 400 and at least partiallyseated in the housing, as further discussed below. FIG. 2B shows theapplicator 400 having the transmitter 500 (not shown) inserted therein.FIG. 2C shows the applicator 500 having the liner 490 (not shown)removed. The removal of the liner 490 exposes an adhesive (not shown) bywhich the on-skin sensor assembly 600 is attached to the host. Afterremoval of the liner the applicator is placed on to the host. In someembodiments, the transmitter 500 may be inserted into the applicator 400after the applicator is placed on to the host. FIG. 2D shows thattrigger (may be referred to interchangeably as “button”) 405 has beenactivated. The activation of the trigger causes the applicator 400 toinsert the sensor into the host, seat the transmitter 500 into thehousing, thereby electrically contacting the sensor to electricalcontacts of the transmitter 500, and detach the applicator 400 from theon-skin sensor assembly 600. This embodiment advantageously allows thedescribed actions to be automatically performed with a single triggeractivation. In some embodiments, the trigger activation also causes theon-skin sensor assembly 600 to begin sensing and transmitting data. Inthis way, the system embodied here allows a user to perform a few simplesteps: insert the transmitter, peel the liner, stick the adhesive toskin and click (activate) the trigger, after which the sensor isautomatically inserted (including needle insertion and subsequentretraction), the applicator is automatically released (from the housing)and optionally the sensor electronics automatically begin the sensorsession, thereby requiring minimal user interaction to initiate a sensorsession.

These results and actions are discussed below in more detail. Whilespecific embodiments are discussed which provide certain mechanicaldevices for performing the functions discussed, one of skill in the artunderstands that various modifications may be made. For example,although the embodiment of FIGS. 2A-2D describes a method whereby thetransmitter 500 is at least partially seated in the housing prior tosensor insertion, modifications could provide for a system wherein thetransmitter 500 is seated in the housing after sensor insertion andapplicator removal.

FIG. 3A is an exploded view of an embodiment of an applicator 400 usedin the process shown in FIGS. 2A-2D. Other implementations may be used.Trigger 405 is attached to front cover (may be referred tointerchangeably as “housing”) 410, and is activated in order to actuatethe applicator 400 to cause the applicator 400 to perform the variousactions described above and below. Front cover 410 is connected to backcover 450, and front and back covers 410 and 450 cooperatively house asensor insertion mechanism. The sensor insertion mechanism includestorsion spring 415, wheel 420, push rod 425, needle hub (also referredto as “needle carrier”) 430, and needle 435, in which the sensor (notshown) is held prior to activation of the trigger 405. In response tothe trigger 405 being activated, the sensor insertion mechanism insertsthe sensor into the host.

The applicator also includes a trigger lock 455, which prevents thetrigger 405 from being activated until the transmitter 500 has beeninserted so as to be at least partially seated in the housing 480. Asdiscussed above and in further detail below, the transmitter 500 is atleast partially seated in the housing 480 by inserting the transmitter500 through the opening in the applicator 400, and is subsequently fullyseated into the housing 480 in response to the trigger 405 beingactivated. A transmitter standoff 460 prevents premature seating of thetransmitter 500 fully into the housing 480. Base 465 is connected to theback cover 450 and receives the inserted transmitter 500. The base 465also guides the transmitter 500 into the housing 480 as the transmitter500 is inserted into the applicator 400.

The housing 480 includes elastomeric seal 475 positioned within thehousing 480 to engage the leading end of the transmitter 500. Inresponse to the applicator 400 being actuated, the transmitter 500 ispressed against the elastomeric seal 475 with the sensor (not shown)between the elastomeric seal 475 and electrical contacts 505 of thetransmitter 500 after the sensor has been inserted into the host.Although a variety of embodiments are illustrated and describedthroughout the present disclosure, such as in FIGS. 3A, 3B, 7, 36 and47-51, for each of the transmitter, electrical contact and/orelastomeric seal designs, it should be understood that each of theembodiments and descriptions associated therewith are wholly or partlycombinable which is generally applicable, particularly with any otherembodiment described herein.

FIGS. 36-38 illustrate a two-part composite seal for sealing around theelectrical contacts 4000 on the transmitter, which features arecombinable, partly or wholly, with other embodiments described herein.In one form, the seal includes a liquid-activated expanding foam 4002and a watertight sealing material 4004. The sealing material 4004 fillsa leakage gap 4006. When the foam expands, as shown in the comparison ofFIGS. 37 and 38, the leakage gap is sealed. In order to get a watertightseal, a small amount of compressive force may be applied to the foam.Due to tolerances of part fit and materials, it is impossible toguarantee a perfect fit in all configurations. This aspect translates tovariations in sealing compressive force. The present embodiment works bythe liquid-activated expanding foam increasing in thickness when exposedto water. This provides an additional gap-filling compressive force onthe sealing surface material.

In some embodiments, the transmitter 500 includes contacts 505 thatinclude a material which, despite being exposed to moisture, do notgenerate a substantial amount of electrochemical current. For example,carbon, a carbon embedded silicone elastomer, a conductive polymer, aconductive salt, and certain metals having the desired property may beused. In some embodiments, the sensor may include a similar material.Such materials reduce or eliminate current caused by an electrochemicalreaction of the contacts with moisture or other contaminants.

Adhesive patch 485 is attached to the housing 480 and to liner 490. Insome embodiments, the adhesive patch 485 is removably attached to theapplicator base 465 on a first side with an adhesive which is weakerthan the adhesive of the second, opposing, side for attaching to thehost. Various adhesive patch embodiments described herein arecombinable, partly or wholly, with other embodiments described herein.In some embodiments, the adhesive patch 485 is attached to a secondliner, which is between the adhesive patch 485 and the applicator base465. In some embodiments, the second liner is removable, for exampleafter the applicator 400 has detached from the on-skin sensor assembly600. The second liner may be removably attached to the applicator base465 with an adhesive.

In some embodiments, the adhesive patch 485 includes an adhesive whichis air permeable and waterproof or water resistant. In some embodiments,the adhesive patch 485 has a backing which is moisture permeable in thearea where the sensor (discussed below) passes through the adhesivepatch 485. In some embodiments, the adhesive patch 485 has a backingwhich is moisture impermeable in an area outside of the housing 480 andthe transmitter 500. The adhesive of the adhesive patch 485 may bepressed onto the host after removal of the liner 490 by pressing on theapplicator 400. In some embodiments, the applicator 490 has a surfacewhich includes texture to aid in the application process. For example,ribs, bumps, or a rough surface may be included to allow for a firm gripon the applicator 490 to be established.

FIG. 3B is an exploded view of another generally applicable embodimentof an applicator 401 and sensor system used in a process substantiallythe same as that shown in FIGS. 2A-2D, which embodiment is combinable,partly or wholly, with other embodiments described herein. FIG. 3C is afront perspective view of the sensor system and applicator of FIG. 3B.Other implementations may be used.

With reference to FIG. 3B, a trigger 406 is attached to a front cover411, and is activated in order to actuate the applicator 401 to causethe applicator 401 to perform the various actions described below. Frontcover 411 is connected to back cover 451, and front and back covers 411and 451 cooperatively house a sensor insertion mechanism. The sensorinsertion mechanism includes torsion spring 416, wheel 421, push rod426, needle hub 431, and needle 436, in which the sensor (not shown) isheld prior to activation of the trigger 406. In response to the trigger406 being activated, the sensor insertion mechanism inserts the sensorinto the host, as described below.

The front cover 411 may, for example, be constructed of any moldableplastic material, such as nylon, polyethylene, polyurethane,ethylene-vinyl acetate (EVA), polyether block amide (PEBAX),acrylonitrile butadiene styrene (ABS), polyether ether ketone (PEEK),polytetrafluoroethylene (PTFE), thermoplastic polyetherimide (ULTEM), orany other material. In some embodiments, the front cover 411 isconstructed of polypropylene, which may provide desirable sounddeadening characteristics when the sensor insertion mechanism isactivated.

The applicator also includes a trigger lock 456, which prevents thetrigger 406 from being activated until the transmitter 501 has beeninserted so as to be at least partially seated in the housing 481. Asdiscussed above and in further detail below, the transmitter 501 is atleast partially seated in the housing 481 by inserting the transmitter501 through the opening in the applicator 401, and is subsequently fullyseated into the housing 481 in response to the trigger 406 beingactivated. A transmitter standoff 461 prevents premature seating of thetransmitter 501 fully into the housing 481. Whereas in the embodiment ofFIG. 3A the trigger lock 455 and the transmitter standoff 460 areseparate pieces, in the embodiment of FIG. 3B these two components arecombined into a unitary structure with the trigger lock 456 and thetransmitter standoff 461 being connected by a living hinge (not shown)or other structure. The living hinge provides a spring return force whenthe trigger lock 456 is pivoted with respect to the transmitter standoff461, as described in more detail below. Further, a cannula 463 extendsfrom the transmitter standoff 461 and receives the needle 436 to provideadditional column strength to the needle 436. The cannula 463 alsoisolates the needle 436 from the elastomeric seal 476, thus eliminatingany potential of the needle 436 to drag broken-off portions of seal 476into the body. It also eliminates any potential friction from the needle436 sliding against or piercing through the seal 476.

The cannula 463 may be integral with the transmitter standoff 461, or aseparate piece secured to the transmitter standoff 461. In oneembodiment, the transmitter standoff 461 is a separate piece ofstainless steel tubing. In some embodiments, the inner surface of thetransmitter standoff 461 may include a lubricant to reduce friction withthe needle 436 and the pushrod 426 when the applicator 401 is activated.For example, the lubricant may be a coating of polytetrafluoroethylene(PTFE), poly(p-xylylene) polymer, such as PARYLENE®, ethylenetetrafluoroethylene (ETFE), or silicone.

The back cover 451 includes a base 466 that receives the insertedtransmitter 501. The base 466 also guides the transmitter 501 into thehousing 481 as the transmitter 501 is inserted into the applicator 401.

In this generally applicable embodiment, the housing 481 includes anelastomeric seal 476 positioned within the housing 481 to engage theleading end of the transmitter 501. In response to the applicator 401being actuated, the transmitter 501 is pressed against the elastomericseal 476 with the sensor (not shown) between the elastomeric seal 476and electrical contacts 506 of the transmitter 501 after the sensor hasbeen inserted into the host.

In some embodiments, the transmitter 501 includes contacts 506 thatinclude a material that, despite being exposed to moisture, do notgenerate a substantial amount of electrochemical current. For example,carbon, a carbon embedded silicone elastomer, a conductive polymer, aconductive salt, and certain metals having the desired property may beused. In some embodiments, the sensor may include substantially the samematerial. Such materials reduce or eliminate current caused by anelectrochemical reaction of the contacts with moisture or othercontaminants.

An adhesive patch 486 is attached to the housing 481. In someembodiments, the adhesive patch 486 is removably attached to theapplicator base 466 on a first side with an adhesive that is weaker thanthe adhesive of the second, opposing, side for attaching to the host. Insome embodiments, the adhesive patch 486 is attached to a second liner,which is between the adhesive patch 486 and the applicator base 466. Insome embodiments, the second liner is removable, for example after theapplicator 401 has detached from the on-skin sensor assembly 600. Thesecond liner may be removably attached to the applicator base 466 withan adhesive.

In some embodiments, the adhesive patch 486 includes an adhesive that isair permeable and waterproof or water resistant. In some embodiments,the adhesive patch 486 has a backing that is moisture permeable in thearea where the sensor (discussed below) passes through the adhesivepatch 486. In some embodiments, the adhesive patch 486 has a backingthat is moisture impermeable in an area outside of the housing 481 andthe transmitter 501. The adhesive of the adhesive patch 486 may bepressed onto the host by pressing on the applicator 401. In someembodiments, the applicator 401 has a surface that includes texture toaid in the application process. For example, ribs, bumps, or a roughsurface may be included to allow for a firm grip on the applicator 401to be established.

In a generally applicable embodiment (i.e. independently combinable withany of the aspects or embodiments identified herein), with reference toFIG. 3C, the applicator 401 may comprise one or more features that makethe applicator 401 easier to use and/or more ergonomic than previousapplicators. For example, the illustrated embodiment of the button 406has a concave outer surface, making it easy to locate with one's fingerwithout even having to look. The surface may also have a differenttexture than the front cover 411. For example, the button 406 may bestippled or roughened while the front cover 411 is smooth, or viceversa. The button 406 may also be a different color than the front cover411, such as a sharply contrasting color, thereby making it easier todistinguish visually from the front cover 411.

The illustrated embodiment of the front cover 411 is ergonomicallyshaped, substantially the same as a computer pointing device (mouse), ina manner that allows it to fit comfortably in the palm of the user'shand. For example, the front cover 411 has a domed or convex uppersurface that creates a large surface area for contacting the user'spalm, and concave portions 428 on opposite sides that receive the user'sthumb on one side and fingers on the other side, both of which featuresstrengthen the user's grip on the applicator 401. For increased grip,the concave portions 428 may also be textured, such as stippled orroughened, as described with respect to the button 406.

The ergonomic shape of the applicator 401 provides at least oneadditional benefit beyond making the applicator 401 easier and morecomfortable to grip. For example, many applicators for continuousanalyte sensors that are on the market today have an appearance thatresembles a syringe. These applicators include a tubular portion thathouses a piston-type drive that propels the needle to implant the sensorunder the skin. Patients with diabetes understand that many syringesinclude needles, and needles evoke memories of oftentimes painful fingerpricks to obtain blood samples and/or sensor implantations that may alsobe painful. Thus, the syringe-like appearance of many applicators maymake them less attractive to patients. The present embodiments solvethis problem by providing an overall appearance that resembles acomputer mouse more than a syringe.

Also as shown in FIG. 3C, one or more embodiments of the presentapplicators may include score marks 492 on opposite sides of the base466. The score marks 492 are substantially aligned with the lower end ofthe cannula 463 (FIG. 9A). The lower end of the cannula 463 is where theneedle exits during the sensor insertion process, and thus substantiallycorresponds with the location on the host's skin where the sensor willbe implanted. Thus, the score marks 409 assist the host in identifyingexactly where the sensor will be placed in the skin. This aspect isadvantageous, as the host may prefer to vary the location of the sensorfrom one implantation to the next so as to avoid irritating any one areaof the skin.

FIG. 4 is a cross-sectional view of the applicator of FIG. 3A prior toinsertion of the transmitter 500, which embodiment is combinable, partlyor wholly, with other embodiments described herein. In one form,automatic release of the applicator from the housing after sensorinsertion and transmitter seating is provided. This figure illustratesthe mechanisms for attachment of the applicator to the housing asshipped to the patient, or prior to the automatic release resulting fromsensor insertion. As illustrated, the back cover 450 holds a nose 484 ofthe housing 480 and the projection 466 on the applicator snap arms 495hold a tail 487 of the housing 480.

As shown, the front cover 410 is connected with the back cover 450. Thefront cover 410 and the back cover 450 form a cavity having the sensorinsertion mechanism therebetween. As discussed above the sensorinsertion mechanism includes torsion spring 415, wheel 420, push rod425, needle hub 430, and needle 435. Push rod 425, needle hub 430, andneedle 435 are not shown in FIG. 4 because they are not in theillustrated plane of the cross-section of the applicator.

A portion of trigger 405 is shown in a cavity of the front cover 410,and a portion of trigger lock 455 is shown within the front and backcovers 410 and 450. The trigger locking function of the trigger lock 455is not represented in this figure because the portions of the trigger405 and the trigger lock 455 related to the function are not in theillustrated plane of the cross-section of the applicator.

Applicator base 465 is connected to the bottom portion of the back cover450, and housing 480 is held in the applicator by the back cover 450 andprojections 466 of the snap arms 495 in the applicator base 465.Optionally, adhesive patch 485 is attached to the housing 480, but isnot attached to the applicator base 465 or the back cover 450.Elastomeric seal 475 is not shown because it is not in the illustratedplane of the cross-section of the applicator. Furthermore, liner 490 isnot shown as it has been removed.

In some embodiments, the applicator includes a mechanism that creates aseating force, which pulls the transmitter 500 into the partially seatedposition within the housing 480. For example, the applicator may apply aseating force to the transmitter 500 to hold the transmitter 500 in apartially seated position within the housing 480 of the applicatorduring sensor insertion. The transmitter seating force may be about 0.25lbs. to about 3 lbs, for example, while a sealing force, which isapplied to the sensor after the applicator trigger 406 is activated, maybe at least two times more than the transmitter seating force, such as3×, 4×, 5×, 10×, 15×, 20×, etc. The applicator prevents the transmitter500 from becoming fully seated within the housing 480 until after sensorinsertion. The fully seated position within the housing 480, whichoccurs after sensor insertion, provides for an electrical connection ofthe sensor with the transmitter 500 and a seal 475 of the electricalconnection. This configuration advantageously allows the transmitter 500to be pre-seated (partially seated) by a user prior to sensor insertion,for example before the assembly is placed on a position on the body thatmay be difficult to reach, and ensures that a seal is formed at theelectrical connection of the sensor with the transmitter 500, which isfully seated only after sensor insertion.

FIGS. 5A-5C are rear perspective views of select components of theapplicator 401 at progressive stages in a method of inserting thetransmitter 501 into the applicator 401 in one generally applicableembodiment, which is combinable, partly or wholly, with otherembodiments described herein. For clarity, and with reference to FIG.5A, only the following components are shown: the trigger 406, thetrigger lock 456, the transmitter standoff 461, portions of the base466, the housing 481, and the transmitter 501.

In some embodiments in which the system is designed for pre-seating ofthe transmitter prior to activation of the trigger (and subsequentsensor insertion and automatic full transmitter seating), a mechanismmay be provided that prevents the trigger 406 from being actuated priorto partial seating of the transmitter 501 within the housing 481. Themechanism is designed to avoid user error, wherein if a user were toforget to pre-seat the transmitter 501 prior to actuating the trigger406, the sensor would be inserted, but the transmitter would not beautomatically fully seated. Accordingly, the trigger lock 455 isprovided to prevent the trigger 406 from being actuated prior to thetransmitter 501 being partially seated in the housing 481. In theillustrated embodiment, upon pre-seating (partial seating), thetransmitter 501 engages the trigger lock 456, which disengages thetrigger lock 456 from the trigger 406, allowing the trigger 406 toactuate. This process is described in further detail below. Also, insome embodiments, design modifications that achieve the same resultcould be used.

At the point of the application process shown in FIG. 5A, thetransmitter 501 is poised for insertion into the base 466 and thehousing 481. Rounded corners 470 at the leading end of the transmitter501 contact rounded inner end surfaces 469 of a pair of spring arms 468that are integrated into the base 466. A gap 471 between the spring arms468 is narrower than a width of the transmitter 501. Thus, as thetransmitter 501 is advanced into the base 466, the rounded corners 470bear against the rounded inner end surfaces 469 and force the springarms 468 apart. Corners at the trailing end of the transmitter 501include protruding tabs 472 and recesses 473 that engage the spring arms468 as the transmitter 501 advances farther into the base 466, asdescribed further below. A height of each of the tabs 472 is less than aheight of the transmitter 501, and the tabs 472 are located toward thelower surface of the transmitter 501.

With reference to FIG. 5B, each of the spring arms 468 includes anundercut portion 474 having a recess beneath. Further, a height of eachof the tabs 472 is less than a height of the transmitter 501, and thetabs 472 are located toward the lower surface of the transmitter 501.Thus, as the transmitter 501 advances through the position shown in FIG.5B, the tabs 472 pass through the recesses beneath the undercut portions474. At this stage, the undercut portions 474 bear down on the tabs 472.Thus, as the tabs enter the recesses beneath the undercut portions 474,the force profile on the transmitter 501 transitions from a lateralsqueezing force to a combination of lateral squeezing and downward(toward the host's skin) force. Also, as the rounded inner end surfaces469 of the spring arms 468 wrap around the cammed surfaces of thetransmitter, the seating force engages and pushes the transmitterforward.

With reference to FIG. 5C, with further advancement of the transmitter501, eventually the undercut portions 474 come to rest in the recesses473 at the trailing corners of the transmitter 501. As the undercutportions 474 enter the recesses 473, the stored spring force in thespring arms 468 relaxes slightly as the spring arms 468 move toward oneanother. This movement generates a force in the direction of advancementof the transmitter 501 as the undercut portions 474 bear on rearwardfacing surfaces of the recesses 473. This force not only draws thetransmitter 501 into the housing 466, but also aids in retaining thetransmitter 501 within the housing 466. And, in the position of FIG. 5C,the transmitter 501 is prevented from further inward movement because itcontacts the transmitter standoff 461, which is in a fixed positionwithin the applicator 401. Thus, at the point of the application processshown in FIG. 5C, the transmitter 501 is held in place by the springarms 468 and transmitter standoff 461, whereby the transmitter is“partially seated” within the housing 481. In some embodiments, othermeans of drawing the transmitter 501 into the housing 466 may be used inplace of, or in addition to, the spring arms 468. For example, one ormore magnets may be positioned on or within the housing 481 and/or thetransmitter 501.

Further, as the transmitter 501 advances from the position of FIG. 5B tothe position of FIG. 5C, it contacts the trigger lock 456, causing thetrigger lock 456 to pivot upward with respect to the transmitterstandoff 461 and moving out of the path of the trigger 406. The trigger406 is thus armed and the applicator 401 is ready to fire. If thetransmitter 501 is subsequently backed out of the housing 481, thetrigger lock 456 may advantageously pivot back to its original positionunder the influence of a return spring force, gravity, etc. For example,the trigger lock 456 may be attached to the transmitter standoff 461with a living hinge that creates the return spring force. This featurerelocks the trigger 406 to prevent accidental firing.

In some embodiments, the applicator 401 provides one or more tactile,auditory, or visual indications that the transmitter 501 has beenproperly inserted into the applicator 401. For example, the transmitter501 being drawn in indicates that the applicator 401 has received thetransmitter 501 to the extent permitted by the transmitter standoff 461.In addition, because the transmitter standoff 461 prevents furtherforward movement of the transmitter, the transmitter 501 cannot befurther advanced. In some embodiments, the drawing in of the transmitter501 causes an audible click. In some embodiments, the applicator 401 hasan opening so that the inserted transmitter 501 is visible through theopening once inserted. The transmitter 501 may have a mark, which, whenvisible through the opening indicates that the transmitter 501 isproperly inserted into the applicator 401. Similarly, the position ofthe drawing mechanism may be visually indicated so as to indicate properinsertion.

In certain embodiments, contours of the transmitter 501 and the springarms 468 are tailored to provide a constant insertion force. That is, asthe user is inserting the transmitter 501, the amount of force appliedto the transmitter 501 is constant from the beginning of the process tothe end. This aspect provides a smooth insertion process that aids inpreventing misalignment or breakage.

Further, contours of the transmitter 501 and the spring arms 468 may betailored to reduce the insertion force that the user must apply topartially seat the transmitter while at the same time increase thesealing force between the seal 476 and the sensor 200. In oneembodiment, the insertion force necessary to partially seat thetransmitter may be about 0.25 lbs. to about 3 lbs., such as about 0.5lb. or 1 lb., while the sealing force may be up to 20 times greater thanthe insertion force, such as 2-3 times greater.

In some embodiments, the spring arms 468 may be pre-loaded with storedenergy, and partially seating the electronics unit within the housingreleases the stored energy. Also in some embodiments, the spring arms468 may be pre-loaded with stored energy, and activating the trigger 406releases the stored energy.

FIGS. 5D and 5E are rear cross-sectional perspective views of theapplicator 400 of FIG. 3A during insertion of the transmitter 500, andillustrate a generally applicable embodiment, which is combinable,partly or wholly, with other embodiments described herein. These viewsshow an embodiment of the trigger lock 455 movement as a result ofinserting the transmitter 500 into the applicator 400. As thetransmitter 500 is drawn into the applicator 400, prior to engaging thetransmitter standoff 460, the transmitter 500 engages the trigger lock455. Further movement of the transmitter 500 until engaging thetransmitter standoff 460 causes the trigger lock 455 to changepositions. In the new position, the trigger lock 455 no longer preventsthe trigger 405 from being activated. Accordingly, once the transmitter500 is inserted into the applicator, the applicator 400 may be actuatedby the trigger 405.

FIG. 5D shows the applicator 400 with the transmitter 500 partiallyinserted therein (but not partially seated). The transmitter 500 hasengaged the trigger lock 455, but has not yet engaged the transmitterstandoff 460. The trigger lock 455 has not been moved and engages thetrigger 405 so as to prevent the trigger 405 from moving. Accordingly,the trigger 405 cannot be activated.

FIG. 5E shows the applicator 400 with the transmitter 500 partiallyseated within the housing 480. In this position, the transmitter 500 ispressed against the transmitter standoff 460 by the contact projections468 on the spring arms 468. As shown, the trigger lock 455 has beenmoved by the transmitter 500, and no longer prevents the trigger 405from being activated. It should be noted that although one embodiment ofa sliding switch trigger is shown, a variety of mechanisms, includingpush buttons, rotating triggers, or the like, that can be configured toinitiate the sensor insertion described herein, can be used with theembodiments herein.

Referring now to sensor insertion, following actuation of the trigger406, an example embodiment of a sensor insertion mechanism is describedbelow. The sensor insertion mechanism is a scotch yoke that convertsrotational motion of the wheel 421 into linear motion of the needle hub431 suitable to insert the needle 436 and the sensor through the skin ofthe host, and to subsequently retract the needle 436 back into theapplicator 401, leaving the sensor under the skin, all in one continuousmotion. This design is particularly advantageous in reducing the numberof complex parts often seen with prior art devices, and further providesa smooth and controlled sensor insertion and needle removal process.However, other sensor insertion mechanism designs can be used instead ofor combined with other aspects of the system described herein.

FIGS. 6A-6D are front perspective views of select components of theapplicator 401 of FIG. 3B at progressive stages in a method ofactivating the trigger 406 and inserting the needle 436 and the sensorinto the host. For clarity, and with reference to FIG. 6A, only thefollowing components are shown: the wheel 421, the pushrod 426, theneedle hub 431, the trigger lock 456, the transmitter standoff 461, andportions of the base 466.

FIG. 6A shows the applicator 401 as it appears with the transmitter 501partially seated in the housing 481 prior to the trigger 406 beingactivated. For clarity, the housing 481 is not shown in FIGS. 6A-6D. Asshown in FIG. 6A, the trigger lock 456 is pivoted upward by contact withthe transmitter 501 so that it does not prevent activation of thetrigger 406. In this position, the torsion spring 415 (not shown inFIGS. 6A-6D) applies a torque to the wheel 421, which applies a linearforce to the needle hub 431 because a tab 423 on the backside of thewheel 421 resides in a channel 427 of the needle hub 431. However, thetrigger 406, having not been activated, prevents the wheel 421 fromrotating. With reference to back to FIG. 3B, an underside of the trigger406 includes a tab 408 that bears against a flange 412 on the wheel 421,thereby preventing rotation of the wheel 421 until the trigger 406 isactivated. A surface of the tab 408 that bears against the flange 412has a predetermined angle that causes the spring-loaded wheel 421 toapply an outwardly directed preload to the button 406. The preloadreduces play in the button 406 that might result from manufacturingtolerances, and also reduces the chances of the applicator 401misfiring. In one embodiment the preload force may be about 0.5-5 lbs.,such as about 2-3 lbs.

FIG. 6B shows the applicator 401 and the sensor insertion mechanismafter the trigger 406 has been activated and while the wheel 421 isrotating. The host activates the trigger 406 by pushing it inwardly withrespect to the front cover 411 (FIG. 3B). This motion is in contrast tothe embodiment of FIG. 3A, in which the trigger 405 is activated bysliding it parallel to a front surface of the front cover 410. Once thetrigger 406 is pushed, the tab 408 on the underside of the trigger 406moves to a position below a plane of the flange 412 so that the wheel421 is free to rotate in response to the torque applied by the torsionspring 415. As the wheel 421 rotates, the tab 412 applies a downwardlinear force to the needle hub 431 via the channel 427. As shown, theneedle hub 431 and the needle 435, which is connected to the needle hub431, have changed positions as a result of the wheel 421 rotating about90°. During this rotation, the tab 412 slides across the channel 427 asthe needle hub 431 moves downward. As shown, the needle 435, containingthe sensor, is extended. The position of the needle hub 431 and theneedle 435 in FIG. 6B represents the maximum extension of the needle435. If the housing 481 were attached to a host, the needle 435 would bepenetrating the skin of the host to insert the sensor into the host.

In order to ensure successful insertion despite different tissue typesand manufacturing variability, the torsion spring 416 preferablyprovides enough torque to cause the needle 435 to accelerate to avelocity higher than desired for some hosts. However, under somecircumstances, excessive velocity can cause unnecessary tissue damage.Thus, in some embodiments a speed regulator may be included.

For example, in some embodiments the velocity of the needle can bereduced by determining an appropriate mass of the needle hub, or anotherelement that moves with the needle. In other embodiments, a flywheel maybe used. In still other embodiments, movement of the sensor insertionmechanism may include a piston slidably engaged in a chamber, where thechamber has an aperture allowing a fluid, such as air, to enter or exitthe chamber to facilitate movement of the piston. The relative sizes ofthe piston, chamber, and aperture can be selected to cause the needle tohave a desired maximum velocity for the torque of the spring and themass of the load. In some embodiments, a speed governor with feedbackcontrol may be used. For example, an air paddle or propeller may beconnected to the needle hub such that as insertion velocity increases,air resistance increases. A centrifugal brake may be used, where weightsare attached to an axle rotating at a speed proportional to the velocityof the needle by a flexible tether. As the velocity increases theweights are forced farther away from the axle and closer to a frictionalsurface. With sufficient velocity, the weights rub against thefrictional surface, limiting the rotational velocity of the axle andalso the velocity of the needle.

FIG. 6C shows the applicator 401 with the wheel 421 having rotated about180° after the trigger 406 has been activated. In this position, theneedle hub 431 has moved back up and away from the host's skin as thetab 423 moves further to the left in the channel 427 and continues toimpart linear motion to the needle hub 431 as the wheel 421 rotates. InFIG. 6C, the wheel 421 is still rotating, but the needle 435, stillattached to the needle hub 431, has been retracted and is within theapplicator 401. The sensor 200, however, remains in the host because ofthe pushrod 425. The function of the pushrod 425 is explained in moredetail below.

FIG. 6D shows the applicator 401 with the wheel 421 having rotated about270° after the trigger 406 has been activated. This is the final restingposition of the wheel 421. For example, there may be a hard stop thatthe wheel contacts to interrupt its rotation. Further, as described inmore detail below, during this step, the transmitter standoff 461 movesto allow the transmitter 501 to advance into the housing 481.

In the above embodiment, full seating of the transmitter 501 within thehousing 481 occurs as part of the sensor insertion process. In someembodiments, the transmitter 501 may be engaged with the housing 481after the sensor has been implanted within the host. For example, theapplicator may not include a provision for receiving the transmitter501. After the sensor has been inserted and the housing attached to thehost, the host may engage the transmitter with the housing to completethe application process.

FIG. 7 is a front perspective view of components of the sensor system ofFIG. 3B, including the transmitter 501, which is generally combinable,partly or wholly, with other embodiments described herein. In one form,a leading end of the transmitter 501 includes arrows 503 whoseorientation corresponds to the proper direction of insertion into thehousing 481. The arrows 503 thus aid the user in properly orienting thetransmitter 501 for coupling with the housing 481, thereby reducing thechance of an improper insertion. As shown in FIG. 5A, the housing 481may include corresponding arrows 503′ that further aid the user inproperly inserting the transmitter 501 into the housing 481.

FIGS. 8A and 8B are front cross-sectional perspective views of thehousing 480 and the transmitter 500 of FIG. 3A after the transmitterstandoff 460 has been moved. FIGS. 8A and 8B show a mechanism forconnecting the sensor to contacts 505 on the transmitter 500 as thetransmitter 500 is fully seated into the housing 480. While not shown,in FIG. 8A the transmitter standoff 460 is no longer between thetransmitter 500 and the elastomeric seal 475, and the transmitter 500 isfree to move farther into the housing 480. Because of the force exertedon the transmitter 500 by the spring arms 468, the transmitter 500 ispushed farther into the housing 480 and is fully seated therein. Theillustrated embodiment shows the sensor 200 piercing through the seal475, however the sensor can be next to or behind the seal in someembodiments. It is noted that the internal workings of the transmitterhave been omitted for simplicity.

As shown in FIG. 8B, the transmitter 500 is pressed against theelastomeric seal 475 with the sensor 200 pressed between the contacts505 of the transmitter 500 and the elastomeric seal 475. As a result, asa consequence of the needle hub retracting, the transmitter standoff 460is moved, and the transmitter 500 is seated into the housing 480 suchthat the transmitter 500 secures the sensor 200 and the contacts 505 ofthe transmitter 500 engage the sensor 200. In some embodiments, the timebetween the sensor 200 being inserted into the host and the transmitter500 securing the sensor is less than about 1 s, about 0.5 s, or about 1ms. Advantageously, this provides for a quick and controlled seal to beformed around the electrical connections between the sensor andelectrical contacts 505 of the transmitter 500, thereby reducingopportunity for the sensor to be disturbed by external influences.Further, this seal is advantageously performed by the user, not at thefactory, which allows the device to use a needle not having alongitudinal channel, which further achieves a less painful insertionwith a smaller gauge needle. Further, in systems where the sensor ispre-terminated (electrical contact) and sealed as part of a housingassembly, these steps are part of the manufacturing process, which addsto the cost. The user making the electrical contacts and seal eliminatesthose manufacturing steps and reduces manufacturing costs. However, insome embodiments wherein the sensor electronics are integral with (anddisposable with) the sensor and housing, the electrical connectionbetween the sensor and transmitter contacts can be formed at thefactory. Similarly, in some embodiments wherein the needle stays on thesensor housing during the sensor session, the electrical connectionbetween the sensor and transmitter contacts can also be formed at thefactory. Accordingly, partial-seating of the transmitter may not berequired in all embodiments.

In some embodiments, the contacts 505 are more rigid than the sensor200, and the contacts 505 press the sensor 200 into the elastomeric seal475. Also in some embodiments, the elastomeric seal 475 is compressedand conforms to the sensor 200 to form a high friction contact with thesensor 200 and to form a seal around the sensor 200.

In some embodiments, a high tack gel, a pressure sensitive adhesive(PSA), or a two part adhesive may be used. For example, some embodimentsuse an epoxy having two compounds that mix as part of the applicator 400actuation and subsequently cure. In some embodiments, the PSA, the epoxycompounds, or other adhesive material may be enclosed in a flexiblecontainer. When the transmitter 500 is seated into the housing 480 thecontainer may be compressed so as to release the material. The releasedmaterial then secures and seals the sensor 200. Holes in the containerthrough which the material escapes may be either formed duringmanufacturing or as a result of the compression, or both.

In some embodiments, additional or alternative mechanisms may be used tosecure the sensor 200 in place and to form a seal around the sensor 200.For example, mechanical structures, such as a clamp attached to eitherthe housing 480 or the transmitter 500 and grasping a portion of thesensor 200 may be used. Alternative examples of mechanical structuresinclude a wedge applying pressure to the sensor 200, a barb, a one-wayvalve, or a tension lock, for example. In the embodiment illustrated,the sensor 200 is bent by the compression force of the transmitter 500against the housing 480. In this way, the sensor is secured or retainedwithin the assembly with a retention force of at least about 0.1, 0.2,0.3, 0.4, 0.5, 1 or 2 pounds when subjected to a standard pull test orpush test (after insertion of the sensor through the housing). In someembodiments, such as the embodiment wherein the sensor is kinked, itwill tend to bind by compression against the contacts of thetransmitter, making the sensor particularly resistant to pushing (forexample from the body if, for example, the sensor were to be inserted ata site of dense tissue, such as muscle). The sensor may even exhibit aresistance to pushing that is greater than its resistance to pulling.This resistance is such that the sensor remains attached to the assembly(and not in the skin of the patient), when the sensor session has endedand a user removes the system from the skin by peeling back theadhesive.

FIGS. 39-41 illustrate various geometries for how the upper end of thesensor may be bent in order to create a retention force to hold itinside the lumen of the deployment needle, as discussed above, whichgeometries are combinable, partly or wholly, with other embodimentsdescribed herein. Example bend geometries include a cosine function(FIG. 39), a sine function with two inflections (FIG. 40), or a sinefunction with three inflections (FIG. 41). Other geometries arepossible, and the foregoing three are just examples. With the presentembodiments, the sensor wire can be front-loaded (or back-loaded)without fear of scraping the wire against the bevel of the needle. Thebend geometry also provides sensor retention within the needle and alarger surface area for the pushrod to contact. Further, the roundedbend geometries allow the sensor wire to be in-line with the exceptionof the bent portion such that the wire is essentially straightthroughout and centered throughout the needle lumen. Another advantageis that the rounded bend is a form of sensor retention through a piercedseal as it increases the pull resistance of the sensor, or the forcenecessary to pull the sensor out from the pierced seal.

In some embodiments, once the sensor 200 is inserted into the host, thesensor 200 is surrounded by an elastomeric seal to secure the sensor 200in place. For example, as part of the sensor insertion, the needle 435may insert the sensor 200 into the host through the elastomeric seal 475or through another elastomeric seal, such as a septum seal (not shown).Subsequently, when the transmitter 500 is seated in the housing 480, thetransmitter 500 compresses the elastomeric seal to secure the sensor 200and to form a seal around the sensor 200.

In some embodiments, the sensor 200 is held in place by multipleelastomeric seals. For example, five seals may be used, wherein in afirst set comprising the first, third and fifth seals is aligned, and asecond set comprising the second and fourth seals is aligned, but thefirst and second sets are offset from each other. When the transmitter500 compresses the seals, the misalignment of the sets causes differentforces to be applied to the sensor 200 by the seals of each set.Accordingly, the sensor 200 does not maintain a linear state, despitehaving been threaded through the seals with a linearly moving needle.The nonlinear configuration increases the securing and sealing force ofthe seals.

In some embodiments, the offset sets of seals may be compressed when thesensor 200 is threaded therethrough, and subsequently uncompressed. Whenuncompressed, the offset configuration of the sets causes differentforces to be applied to the sensor 200 by the seals of each set. In someembodiments, the sensor 200 is inserted all the way through one of theseals, such that once the needle retracts, the end of the sensor iscloser to the host than the one seal. The one seal is compressed eitherduring insertion of the sensor 200, or after, or both, so that after theretraction of the needle, the slit formed in the one seal by the needletravelling therethrough moves away from the end of the sensor 200 suchthat if the sensor were to be forced back to the one seal, the sensorwould push against the one seal instead of moving back through the slit.Similarly other seals may be compressed during and/or after sensor 200insertion in such a way that the sensor 200 is not aligned with the slitin the one seal.

In some embodiments, once the sensor 200 has been inserted into thehost, the sensor 200 has a ferrule around it to form a seal. Forexample, the sensor 200 may extend through an elastomeric taperedferrule that is set in a rigid sleeve conforming to the same taper asthe ferrule. Either during the insertion process, or as a result of thetransmitter 500 being seated, or both, the ferrule receives pressure,which causes it to compress against the sleeve and against the sensor200 to secure the sensor 200 and to form a seal around the sensor 200.

FIGS. 9A-9E are front cross-sectional perspective views of the sensorinsertion mechanism at various stages in a method of actuating theapplicator 401 with the trigger 406, which embodiment is combinable,partly or wholly, with other embodiments described herein. FIGS. 9A-9Dshow an embodiment of pushrod actuation, and substantially correspond tothe actuation timing of FIGS. 6A-6D, respectively. In some embodiments,wherein the sensor is not attached to the sensor insertion mechanism,and because the sensor is “handed off” from the applicator to theon-skin sensor assembly, the independent movement of the sensor relativeto other portions of the applicator and on-skin assembly is controlledat least partially by the pushrod 426. In general, the pushrod ispositioned within the needle 436 prior to sensor insertion, and isconfigured to move with the needle as the needle is inserted into thehost, and to remain fixed as the needle is removed from the host,whereby the pushrod is configured to prevent the sensor from beingretracted from the host with the needle. In this example embodiment, thepushrod 426 initially (FIG. 9A, 9A′) is latched onto the needle hub 431to cause the pushrod to move with the needle during insertion of theneedle into the host. When the needle is in its farthest extendedposition (FIG. 9B, 9B′), the pushrod becomes unlatched from the needlehub and engages the back cover of the applicator, thereby immobilizingthe pushrod as the needle hub retracts into the applicator, as describedfurther below.

FIGS. 9A and 9A′ show the configuration of the pushrod 426 and theneedle hub 431 when the transmitter 501 is partially seated within thehousing 481 and prior to the trigger 406 being activated. It is notedthat the internal workings of the transmitter have been omitted forsimplicity. The wheel 421 has not rotated, and the needle 436 and needlehub 431 are within the applicator 401. As shown in FIG. 9A′, the end426′ of the pushrod 426 opposite the needle is coupled to the needle hub431. The opposite end of the pushrod extends into the back end of theneedle 436 and is adjacent to the sensor 200, which is inside the needle436.

FIGS. 9B and 9B′ show the pushrod 426 and the needle hub 431 after thewheel has rotated about 90 degrees in response to the trigger 406 beingactivated. As shown, the pushrod 426 has traveled with the needle hub431 during the extension of the needle 435. Accordingly, the oppositeend of the pushrod still extends into the needle 435. The top end of thepushrod 426 engages a notch 453 in the back cover 450 as the needle hub431 moves upward. The notch 453 prevents the pushrod 426 from furthermovement. The pushrod 426 thus disengages the needle hub 431, pushingthe sensor 200 out of the needle 436 as the needle hub 431 retracts.

FIG. 9C shows the pushrod 426 and the needle hub 431 with the wheel 421having rotated about 180 degrees after the trigger 406 has beenactivated. As shown, the needle hub 431 has moved so as to retract theneedle 435 from the host. The top end of the pushrod has not moved andcontinues to be engaged with the notch 453 in the back cover 450. Theopposite end of the pushrod has remained in the needle 435 as the needle435 has been removed from the host. Therefore, the pushrod has pushedagainst the sensor 200 within the needle 435 to prevent the sensor 200from exiting the host with the needle 435. In some embodiments, thepushrod 426 may be further retracted by a mechanism that removes thepushrod 426 from the notch 453 and reconnects the pushrod 426 to aholder (not shown) on the needle hub 431 prior to the full retraction ofthe needle.

FIGS. 9D and 9E show the needle hub 431 after the wheel has rotatedabout 270 degrees in response to the trigger 406 being activated, asdiscussed above. The sensor 200 has been inserted into the host and theneedle hub 431 has been moved by the wheel projection 422. The needlehub 431 has engaged the transmitter standoff 461 and lifted thetransmitter standoff 461 out of the path of the transmitter 501. As aresult, the transmitter standoff 461 no longer prevents the transmitter501 from moving in response to the spring arms 468. With the transmitterstandoff 461 lifted, the applicator spring arms 468 fully seat thetransmitter 501 and compress the seal 476.

FIG. 9F shows that the transmitter 500 has traveled sufficiently thatthe trailing edge of the transmitter 500 no longer contacts theapplicator base 465. Because the trailing edge of the transmitter 500 nolonger contacts the applicator base 465 no longer contacts the housing480. Accordingly, the housing 480 and the transmitter 500 are no longerconnected to the remaining portions of the applicator 400, and theapplicator 400 is detached from the housing 480. The transmitter 500 issecured to the housing 480 because of a protrusion 510 in thetransmitter 500 extending into hole 482 in the housing 480. Othermechanisms may also be used to secure the transmitter 500 to the housing480. In this way, the embodiment described herein allows for automaticsensor insertion, (including needle insertion and removal), transmitterseating (including electrical connection and seal compression), andrelease of the applicator from the housing, all without any userinteraction other than actuating the trigger.

With further reference to FIG. 9E, engagement of the transmitter 501with the elastomeric seal 476 deforms the elastomeric seal 476 to anextent that the upper end of the sensor 200 is kinked in at least oneplace. The kinking increases the force that would be necessary to pullthe sensor 200 out from the space between the transmitter 501 and theelastomeric seal 476. The sensor 200 is thus less likely to be pulledout of that space when the user removes the sensor 200 from his or herskin, which would be undesirable because the sensor 200 may then be leftstuck in the skin.

Material properties of the elastomeric seal preferably provide both goodsealing and maintenance of contact between the sensor and the contactson the transmitter. Materials having a low durometer may provide goodsealing, but if the durometer is too low the sensor may tend to pullaway from the contacts because of relaxation in the sealing material.One material that has been found to produce desired results isthermoplastic elastomer (TPE), particularly VERSAFLEX™ CL2003X TPE,available from Polyone Corporation. However, other materials may beused.

In a generally applicable embodiment, portions of the seal configured tocontact at the sensor contact points are reinforced and/or conductiveparticles are provided in the sealing material, which embodiment iscombinable, partly or wholly, with other embodiments described herein.In one form, pucks formed from a sealing material (e.g., with a higherdurometer than other portions of the seal) are formed or inserted intothe seal, and include conductive particles. In practice the conductivepucks align with the sensor (contact points) after sensor insertion,pressing the sensor against the contacts of the transmitter and ensuringgood electrical connection without sacrificing sealing properties.

With reference to FIGS. 8A and 9A, there are numerous potentialconfigurations for the elastomeric seal 475, 476 with respect to thesensor 200. For example, with reference to FIG. 8A, the sensor 200 maypierce the elastomeric seal 475 in one or more places, and be held inthe elastomeric seal 475 by friction. While FIG. 8A illustrates thesensor 200 piercing the elastomeric seal 475 in two locations, anynumber of locations could be provided.

With reference to FIG. 9A, the elastomeric seal 476 may include a bore900 that receives the cannula 463, and the sensor 200 may extendpartially into the bore 900 or be spaced from the bore 900 as in FIG.9A. When the applicator 401 is activated by pushing the button 406, thesensor will pass through the bore 900 and into the patient's skin, whileengagement of the transmitter 501 with the elastomeric seal 476 deformsthe bore 900 to hold the sensor 200 in the bore 900 with a squeezingforce. In this embodiment, the mating of the sensor 200 with theelastomeric seal 476 is performed by the user rather than themanufacturer. This aspect provides at least one advantage. The sensor200 can be loaded into the needle by passing it through the sharp distaltip of the needle at the time the applicator 401 is assembled. Thisfeature enables the entirety of the applicator 401, minus the sensor200, to be manufactured and assembled in one or more locations and thensent to another location where the sensor 200 is added. The benefit ofthis feature is that security for the sensors, which are oftenmanufactured of precious metals such as platinum, can be tightlycontrolled to reduce the risk of theft.

With further reference to FIG. 9A, at least in part because the sensor200 is not embedded in the elastomeric seal 476 at the time ofmanufacture and assembly, it is not actually attached to any portion ofthe applicator 401. Rather, it is held inside the needle 436 byfriction. However, the diameter of the sensor 200 is less than theinside diameter of the needle 436. Thus, to produce the frictionnecessary to prevent the sensor 200 from falling out, a top end of thesensor 200 may include a bend or kink (not shown) to create a springforce in the sensor 200 when it is inserted into the needle 436, therebycausing various portions of the sensor 200 to bear with force againstthe inside of the needle 436.

FIG. 10 is a front perspective view of the on-skin sensor assembly 1000after the applicator 401 has detached from the housing 481, whichembodiment is combinable, partly or wholly, with other embodimentsdescribed herein. In one form, the assembly 1000 comprises at least thesensor 200 implanted in the skin, the housing 481, the adhesive 485, andthe transmitter 501. In some embodiments, the adhesive patch 485 isremovably attached to the applicator base 465. In such embodiments,activating the trigger 406 may additionally cause an adhesive releasemechanism to actuate. The adhesive release mechanism may, for example,include one or more projections that, when actuated, extend from theapplicator base 465 to the adhesive patch 485 in order to remove theadhesive patch 485 from the applicator base 465. The projections may,for example, be located along a peripheral portion of the applicatorbase 465. In some embodiments, the projections are located adjacent tothe transmitter 501.

FIGS. 11A and 11B are exploded views of generally applicable embodimentsof applicators used in the process shown in FIGS. 2A-2D, whichembodiments are combinable, partly or wholly, with other embodimentsdescribed herein. In one form, with reference to FIG. 11A, theapplicator 1100 is substantially the same to that of FIG. 3A, exceptthat the pushrod 426 of FIG. 3B has been substituted for that of FIG.3A. With reference to FIG. 11B, the applicator 1102 is substantially thesame to that of FIG. 11A, except that the button 1104 is a pushbuttonstyle, like that of FIG. 3B, rather than a sliding button, the frontcover 1106 is shaped somewhat differently, the wheel 421 of FIG. 3B hasbeen substituted, the needle hub 1108 and the trigger lock 1110 havebeen combined into a single piece, like that of FIG. 3B, the back cover1112 is configured somewhat differently, and the shape of theelastomeric seal 1114 has been changed. One aspect of the elastomericseal 1114 that differs from that of previous embodiments is that therelatively low durometer of the elastomeric seal 1114 seals only oneside of the sensor 200, while opposite the sensor is the material of thetransmitter and electrical contacts, which have a relatively highdurometer.

FIGS. 12A-12D illustrate generally applicable embodiments of the housing480, which embodiments are combinable, partly or wholly, with otherembodiments described herein. Each of the embodiments of FIGS. 12A-12Dhave a mechanism for securing the transmitter 500 to the housing 480 byengaging protrusion 510 discussed above with reference to FIG. 10. Inaddition, each of the embodiments of FIGS. 12A-12D have a mechanism forsecuring the transmitter 500 to the housing 480 so that the transmitter500 may not or may not easily be released from the housing 480 until thesystem 600 is removed from the host.

FIG. 12A shows an embodiment of the housing 480 having hole 482, a firsttab 488, and a second tab 489. As discussed with reference to FIG. 10,the protrusion 510 on the transmitter 500 engages the hole 482 so thatthe transmitter 500 is secured to the housing 480. The first tab 488 isflexible, so that when the transmitter is being fully seated into thehousing 480, the first tab 488 flexes so as to provide only minimalresistance to the insertion. Once fully seated, the first tab 488secures the transmitter 500 to the housing 480 until the second tab 489is flexed sufficiently to disengage the first tab 488 from theprotrusion 510. While being flexed, the second tab rotates about an axiswhich is near the end of the first tab 488 defining the hole 482. Oncethe rotation is sufficient, the protrusion 510 disengages from the firsttab 488, releasing the transmitter 500. Because the rotation of thesecond tab 489 is in a direction which is into the page of the figure,away from the transmitter, the second tab 489 may not be substantiallyflexed while the housing 480 is attached to the user. Accordingly, thetransmitter 500 may not be released from the housing 480 while thehousing 480 is attached to the user. In some embodiments, sufficientrotation of the second tab 489 to cause the release also causespermanent damage to the housing 480. For example, the second tab 489 maybreak off.

FIG. 12B shows an embodiment of the housing 480 having hole 482, a firsttab 488, and a second tab 489 having features substantially the same asthe corresponding structures discussed above with reference to FIG. 12A.In this embodiment, steps or notches 492 are formed in the housing 480between the ends of slots 491 to help define the axis of rotation of thesecond tab 489.

FIG. 12C shows an embodiment of the housing 480 having hole 482, a firsttab 488, and a second tab 489 having features substantially the same asthe corresponding structures discussed above. In this embodiment, thefirst tab 488 is bent so as to extend out of the general plane of thehole 482 and the second tab 489. The bent first tab 488 is advantageousbecause the first tab 488 is biased against the transmitter 500 tosecure the transmitter 500 in the fully seated configuration.

FIG. 12D shows an embodiment of the housing 480 having hole 482, a firsttab 488, and a second tab 489 having features substantially the same asthe corresponding structures discussed above. In this embodiment, thefirst tab 488 extends beyond the axis of rotation of the second tab 489defined by a line intersecting the ends of slots 491. With thisstructure, as the second tab 489 is flexed and rotates, the end of thefirst tab 488 will press against the transmitter 500, presenting someresistance to the rotation. The resistance may be overcome by applyingsufficient force to the second tab 489, and once the second tab 489 hasrotated sufficiently, the transmitter will disengage from the housing480 with an audible snap and sudden loss of resistance.

FIGS. 13A-13D show generally applicable embodiments of the housing 480having a hole 482, a first tab 488, and a second tab 489 having featuressubstantially the same as the corresponding structures discussed abovewith reference to FIGS. 12A-12D, and which features are applicable toall aspects and embodiments identified herein. Each of the embodimentsof FIGS. 13A-13D also has a mechanism for securing the transmitter 500to the housing 480 by engaging a second protrusion in the transmitter500. The second protrusion engages the housing 480 at a cutout 493 sothat the transmitter 500 may not or may not easily be released from thehousing 480 until the system 600 is removed from the host even with theaid of a prying tool, such as a screwdriver. In the embodiments of FIGS.13B and 13C the protrusion 510 does not engage the cutout 493 while thetransmitter 500 is being fully seated in the housing 480.

FIG. 14 is a lower plan view of a generally applicable embodiment of ahousing 1400, which embodiment is combinable, partly or wholly, withother embodiments described herein. The housing 1400 is substantiallythe same as the foregoing embodiments, except that the tab 1402 and theslots 1404 have more rounded contours, and the central hole 482 isreplaced with a pair of apertures 1406 on opposite sides of the housing1400. The apertures 1406 receive a pair of corresponding tabs 1408 onthe transmitter 501 to secure the transmitter 501 to the housing 1400.The dual tab mechanism may provide a more secure hold for thetransmitter 501 within the housing 1400. Further, to remove the devicefrom the skin, the user pulls upward on the tab 1402. Thus, providingthe slots on either side of the tab 1402 enables the tab 1402 to flex acertain amount without disengaging the tabs 1404 from the apertures1406, thereby reducing the chance of accidentally removing the devicefrom the skin.

The on-skin sensor assembly should be attached to a host for a limitedperiod of time. Once the time expires, the assembly should be removedand possibly replaced. To prevent inappropriate reuse of the sensor, theapplicator 400 and the on-skin sensor assembly have certain features.For example, in some embodiments, the transmitter 500 may not be removedfrom the housing 480 without destroying the housing 480. In someembodiments, the transmitter 500 may not be removed from the housing 480without removing the adhesive patch from the housing 480 or from thehost.

In some embodiments, when the system 600 is adhered to a user's skin,the skin blocks movement of a lever, which is used to remove thetransmitter 500. The lever is clearly visible and easily accessible whenthe system has been removed for the user's skin, but it can't be useduntil the system 600 is removed. In this way, the transmitter can onlybe detached after the sensor is removed from the body (and is therebyrendered unusable).

In some embodiments, the sensor electronics within the transmitter 500are programmed to analyze the signal, for a signal characteristic thatindicates a sensor has been removed (or inserted) for example, near-zerosignal (or characteristic break-in signature). When the sensorelectronics detect that a sensor has been removed (or inserted) based onanalysis of the signal, certain algorithms can be responsive thereto.For example, the sensor electronics can be programmed to turn off thesystem after the expiration and/or ensure removal of the expired sensorfrom the host.

In some embodiments, the applicator 400 is packaged for distributionwith the housing 480 and seal 475 therein. In some embodiments, thepackaging is at least partially integrated with the applicator 400.

For example, the packaging for the applicator 400 may include the frontcover 410 and the back cover 450. In some embodiments, the port intowhich the transmitter 500 is inserted is covered, for example, by adoor. Likewise, the port through which the sensor is inserted into thehost may be covered, for example, by a door. In some embodiments, one ormore of the doors is removable, for example, with a pull tab.

In some embodiments, the packaging includes liner 490. Accordingly, touse the applicator 400, the applicator 400 is removed from the packagingliner 490 and applied to the host. In this embodiment, removing theapplicator 400 from the packing liner 490 exposes the adhesive on theadhesive patch 485. In some embodiments, the packaging liner is onlyreleasable when the transmitter 500 is pre-seated, or partially seated,for example the liner 490 may be covered by a shield which moves toexpose the liner once the transmitter 500 is partially seated. In someembodiments, the packaging liner 490 includes instructions for use. Insome embodiments, multiple applicators 400 are included on the samepackaging liner. For example, 2, 4, 8, or 12 applicators may be includedon the same packaging liner, for example, via perforated attachment,whereby a kit is provided.

In some embodiments, the applicator includes a protective cover thatattaches to the housing. The protective cover may protect theelectronics unit and the insertion point on the host from dirt, sand,water, etc. The internal portion of the protective cover may conform tothe shape of the applied on-skin sensor assembly 600. In someembodiments, the cover includes multiple or composite layers, and may bewaterproof or water resistant, and may further be air permeable. In someembodiments, the cover is decorative in its shape, color, and colorpatterns. For example, the cover may have an appearance of an animal ora character, e.g., a cartoon character or other animated character. Theprotective cover may have an adhesive that attaches the protective coverto the adhesive patch 485. In some embodiments, the cover is designed toshift the weight or volume off-center, to avoid “hot spots” associatedwith the pressing of the edges of the housing on the skin, therebyavoiding compression artifacts that may occur in the vicinity of thesensor insertion site.

In some embodiments, the applicator inserts the sensor into the host anddetaches from the housing in response to the trigger being activated,but does not seat the transmitter. In such embodiments the transmitteris seated into the housing after the applicator has detached from thehousing. A mechanism described herein may be used to seat thetransmitter into the housing.

In some embodiments, the applicator has a size and shape so that it isconfigured to substantially fit within a palm of a hand, for example,like a computer mouse. Because of the ergonomic shaping, the applicatoris held with a flat wrist, while allowing the trigger to be released. Auser can fully insert the sensor, including transmitter attachment andoptionally start of sensor session with a single hand at any location onthe body reachable by hand, even locations that are awkward to reach.

In some embodiments, once applied, the housing 480 substantially fullyencapsulates the transmitter 500 against the host. In such embodiments,the transmitter 500 is inserted into the housing 480 from the host sideof the applicator 400. In some embodiments, the housing 480 forms ashell which encloses a drawing mechanism and includes a septum throughwhich the needle inserts the sensor. As with the embodiments discussedabove, activation of a trigger causes the needle to insert the sensor,and the transmitter to secure the sensor such that the sensorelectrically contacts the transmitter.

In some embodiments, an alternative sensor insertion mechanism is used.The alternative sensor insertion mechanism is driven by an action fromthe user instead of using energy stored in a spring, which alternativesensor insertion mechanism is combinable, partly or wholly, with otherembodiments described herein. Accordingly, energy for the insertionmovements is provided by the user. For example, to cause a needle toinsert a sensor, the user may squeeze the applicator or otherwise causemovement of a needle carrier. Movement of the needle carrier causes theneedle to be inserted into the host and to be removed from the host.Movement of the needle carrier may also cause results as those discussedabove, such as movement of a transmitter standoff and seating of thetransmitter into the housing. At the end of the movement of the needlecarrier, the needle carrier may press against a bumper so as to causethe deceleration of the needle carrier to be limited instead ofgenerating a shock which would be translated throughout the applicator.

FIG. 15 is a perspective view of another sensor insertion mechanism,utilizing a cam path and cam follower to guide sensor and needleinsertion with subsequent needle retraction, which embodiment includesfeatures that are combinable, partly or wholly, with other embodimentsdescribed herein. FIG. 15 shows an example of a needle carrier 442,which is a cam with two slots 443. In embodiments using a cannula, athird slot may be formed. The slots 443 guide the motion of the needle435 and pushrod 425 by engaging followers. This allows one squeezingmotion to translate to complex in-and-out movements of the needle 435and pushrod 425 without springs or locking mechanisms. FIGS. 16A-16D areperspective views of the needle carrier of FIG. 15 showing use of theneedle carrier 442, which feature is combinable, partly or wholly, withother embodiments described herein. In FIG. 16A the applicator is readyfor actuation. In FIG. 16B the needle 435 is inserted into the host. InFIG. 16C the needle 435 is retracted, leaving the sensor 200. In FIG.16D the needle 435 is retracted so as to not be exposed once theapplicator is removed. In some embodiments, the movement of the needlecarrier 442 also causes the transmitter 500 to be fully seated and to becompressed against an elastomeric seal to seal and secure the sensor200, such as described above.

Aside from cost and reliability advantages, a cam needle carrier resultsin a smoother feel. The slots allow nonlinear translation of squeezingto needle movement. For example, a greater mechanical advantage could begiven for inserting the needle than for withdrawing the needle. In someembodiments, the needle relatively slowly punctures the skin of thehost, and then quickly reaches its full depth to improve the perceptionof accuracy or reduce the perception of insertion depth.

As shown, the pivot point is at the top of the needle carrier 442. Insome embodiments the pivot point is placed at the bottom or the middle.Mechanical advantage and speed of actuation can be tuned by varying thedistance of the slots from the pivot point, by varying the distance ofwhere the user pushes the needle carrier 442 from the pivot point, andby varying the angle of cam rotation for each movement, for example, bymaking the slots steeper or shallower. The pivot point is also shown inline with the followers, but in some embodiments, it is offset to adjustmechanical advantage.

FIGS. 17A and 17B are perspective views of the applicator showing alatching mechanism for the needle carrier, which feature is combinable,partly or wholly, with other embodiments described herein. Theapplicator may be made stick-proof by including a latch 441 at the endof the stroke to lock the cam in its final position. In someembodiments, the latch is flexible and built into the cam, such as thatshown in FIGS. 17A and 17B. FIG. 18 is a perspective view of theapplicator showing another embodiment of a latch 441, which embodimentis combinable, partly or wholly, with other embodiments describedherein.

FIGS. 19A and 19B are perspective views of an embodiment of anapplicator, which embodiment includes features that are combinable,partly or wholly, with other embodiments described herein. As shown,flexible arms 444 draw in and hold the transmitter 500. FIGS. 20A, 20B,and 20C are perspective views of a mechanism for drawing in thetransmitter 500 into the housing. FIGS. 20A, 20B, and 20C show anembodiment of the arms 444 engaging the transmitter 500, which featuresis combinable, partly or wholly, with other embodiments describedherein. In such an embodiment the transmitter 500 is not required totravel unnecessarily. In addition, the elastomeric seal can be thinner,and may not be compressed. Furthermore the arms can be formed togenerate as much force as needed, so that the force applied to thedevice after insertion is not dependent on the user.

Detachment from the transmitter 500 and the housing 480 may be caused bythe cam rotation. For example, at the end of the cam movement, a latchmay be released to disengage the transmitter 500 and the housing 180.FIGS. 21A, 21B, and 21C are perspective views of an embodiment of alatch for a cam, which embodiment is combinable, partly or wholly, withother embodiments described herein. As shown in FIGS. 21A, 21B, and 21C,a front latch 446 is opened by the cam 442. In addition a rear latch 447is manually unhooked by pivoting the cam 442 up. In some embodiments, abump or ramp on the cam 442 causes the cam 442 to push up, giving aclear indication that it is released. Alternatively, the applicatorcould have an integral spring to push it up and away upon release. Thefront or rear latches could be modified accordingly. A springinteracting with the transmitter 500 would be advantageous becauseplastic would not be held under stress during sterilization and shelflife, which could cause the plastic to loose its spring force.

The cam followers slide freely in the slots responsive to manual(user-controlled) and/or automated (e.g., spring-controlled) force.FIGS. 22A, 22B, and 22C are perspective views of embodiments ofmechanisms for reducing play without tight tolerance parts, the slotsmay include a deformable lip which applies a force against thefollowers, which mechanisms are combinable, partly or wholly, with otherembodiments described herein. FIGS. 22A and 22B show embodiments oflips. In addition a relief cut, near each slot may allow for the slotsto flex to reduce play. FIG. 22C shows an embodiment of a relief cut.

FIGS. 23A and 23B are perspective views of an embodiment of a sensorinsertion mechanism 700, which embodiment includes features that arecombinable, partly or wholly, with other embodiments described herein.The mechanism 700 is formed from a single plastic part to which a needleand a pushrod are attached. The mechanism 700 includes three movablesections 702, 704, and 706, separated by live hinges 703, 705, and 707.FIG. 23B shows the movable sections inserted into a vertical slot 708.FIGS. 24A, 24B, and 24C are perspective views showing actuation of themechanism 700. In FIG. 24A, the mechanism 700 is ready for actuation andis placed on the host. In FIG. 24B, section 706 is rotated causingsections 704 and 702 to move toward the host, and causing the needle 710to be inserted into the host. In FIG. 24C, section 706 is furtherrotated causing sections 704 and 702 to move away from the host, andcausing the needle 710 to be retracted from the host, leaving the sensor715 in the host.

FIGS. 25A and 25B are perspective views showing an embodiment of apushrod 720 and its attachment to the mechanism 700, which feature iscombinable, partly or wholly, with other embodiments described herein.As shown, the pushrod 720 has no bonded carrier and is attached to themechanism 700 by attachment elements 725 without adhesive. The pushrod720 is flexible which allows it to stay aligned as it moves to deliverthe sensor, even though the back end is attached to the mechanism 700.

FIG. 26 is a perspective view showing an embodiment of an applicator,which embodiment includes features that are combinable, partly orwholly, with other embodiments described herein. In some embodiments,such as that shown in FIG. 3A6, the applicator may be shaped such that asubstantially oval base substantially perpendicularly extends from asubstantially vertical substantially oval shaped wall. The wallsurrounds a top portion on which the trigger is disposed. In someembodiments, the trigger forms substantially the entire top of theapplicator. In some embodiments, the trigger is covered by a removableliner configured to prevent accidental activation of the trigger.

FIGS. 27A-27D are schematic views of the applicator of FIG. 26,illustrating a method of using the applicator. In some embodiments, suchas that shown in FIGS. 27A-27D, pressing the trigger 105 causes a needlehub 430 to move so as to insert the sensor 200 into the host. Theapplicator pod 401 and trigger 405 are indicated in dotted lines. Withinthe applicator pod 401 a housing 180 with an adhesive 486 is positioned.The adhesive 486 is supported by the rim of the applicator pod 401. Thehousing 180 is held by ribs provided in the pod (not shown). The supportof the rim and the rims allow the full surface area of the adhesive tobe firmly pressed onto the host, enabling attachment of the housing 180without the need to use a second hand or the chance of introducingwrinkles.

The applicator includes a needle 435 that is slidably mounted with aslider 440. The sensor 200 is permanently connected to the electricalcontacts 445, e.g., pre-connected at the factory. The slider is slidablymounted in a hinged frame 455 connected to the housing with hinges 456.The top end of the slider 440 engages with the trigger 405 so that whenthe trigger 405 is depressed, the slider 440 moves downward and theneedle hub 430 forces the needle 435 carrying the sensor 200 into thehost.

In such embodiments, the needle hub may be connected to a slider whichis locked, for example, by a springed latching lock once the sensor hasbeen inserted. Actuation of the lock may provide an audible and/ortactile indication that the sensor is properly inserted.

FIG. 27A shows the applicator as attached to the host. As shown, the rim402 on the applicator pod 401 may be used to exert force on the adhesivewhile the applicator pod 401 is pressed against the host. FIG. 27B showsthe needle 435 inserted into the host. With the depression of thetrigger 405, the slider 440 moves down and the needle 435 is insertedinto the host. Once the needle 435 has been inserted, a springedlatching lock clicks in place, locking the slider 440 and providing anaudible and tactile indication that the sensor has been inserted.

FIG. 27C shows the removal of the applicator pod 401 and the trigger405. The slider 440 may be releasably engaged with the trigger 405during depression of the trigger with a latch (not shown). Once thesensor 200 is inserted into the host the latch may be released torelease the slider 440 from the trigger 405. Alternatively, the slider440 may be connected to the trigger 405 by an adhesive. Once the sensor200 has been inserted, and the springed latching lock has locked theslider, the applicator pod 401 and the trigger 405 are removed such thatthe trigger adhesive releases, it being weaker than the adhesiveattaching the housing 180 to the host. As shown, the slider 440, theneedle hub 430, and the needle 435 remain attached with the sensor 200to the host.

FIG. 27D shows that the slider 440, the needle hub 430, and the needle435 may fold over so as to have a lower profile. Such folding may becaused by a spring causing the slider 440, the hinged frame 455, theneedle hub 430, and the needle 435 to rotate about the hinges 456.

FIGS. 28A and 28B are schematic views of an embodiment of an applicator,which embodiment includes features that are combinable, partly orwholly, with other embodiments described herein. In this embodiment,once the sensor 200 is inserted into the host, a needle spring 406pushes the needle away from the host after the sensor 200 is insertedinto the host.

In some embodiments, the applicator has an exterior formed at leastpartly of a hard plastic. In some embodiments, an elastomer is used atleast partly to relieve strain caused, for example, by movement of thehost. The elastomer may be used around the perimeter of the applicator.

FIGS. 29A and 29B are perspective views of an applicator 400 in apackage 800, which is usable with any of the applicator embodimentsdescribed herein. In one form, if a user forgets to insert thetransmitter 500 before placing the applicator 400, the sensor may bewasted because the applicator cannot be triggered without thetransmitter. In addition, handling the applicator with an insertedtransmitter can result in undesired activation of the trigger. To remindusers to insert the transmitter 500 and to prevent undesired activationof the trigger, package 800 allows for insertion of the transmitter 500while the applicator 400 is still in the package 800.

In some embodiments, the package 800 includes a shell 810 in which theapplicator 400 is held in a fixed position. In some embodiments, theshell 810 is vacuum formed. The shell 810 is sealed with a removable tab820, which may be peeled off of the shell 810 to expose the applicator400. The applicator 400 is oriented in the package 800 so that a cavity830 into which the transmitter 500 is to be inserted is accessible oncethe tab 820 is removed. The exposed cavity 830 provides a visual cue orreminder to the user that the transmitter 500 should be inserted intothe applicator 400. In some embodiments, a portion of the tab 820 whichis exposed by its removal may have information, such as graphics,thereon which provides instructions or a reminder to insert thetransmitter 500 into the cavity 830.

In some embodiments, the shell 810 is rigid, so that the shell 810shields the trigger 405 to substantially prevent access to the trigger405 while the applicator 400 is still in the shell 810. Accordingly,undesired activation of the trigger is substantially prevented.

In some embodiments, the housing 480 has one or more openings aroundtheir perimeter and/or side surfaces so that moisture which enters theapplicator 400, can quickly be removed. In some embodiments, the housingincludes a wicking material which wicks moisture to the perimeteropenings. For example, the adhesive patch 485 may include a wickingmaterial, such as a woven or a non-woven wicking material. In someembodiments, the housing 480 has a channel formed therein which drawsmoisture from within the applicator 400 toward the outside. In someembodiments, all or substantially all water is removed from theapplicator 400 within about 15-30 minutes.

When the sensor 200 is inserted into the host, blood may be released bythe host. In some embodiments, the blood is collected in a bloodreservoir, for example, in the housing 480. The blood may be transmittedto the reservoir through a weep hole in the housing by a capillarychannel or wicking material. In the reservoir, the blood may beabsorbed, for example, by a sponge, a super absorbent polymer, a wickingmaterial. In some embodiments, the reservoir and/or the insertion siteon the host are aerated to, for example, allow for drying and to reducebacterial growth.

FIGS. 30A-30D are illustrations of generally applicable embodiments ofhousing 480 showing the host side of the housing 480, which embodimentsare combinable, partly or wholly, with other embodiments describedherein. The housing 480 has hole 494 through which the needle 435passes, and one or more capillary channels 496, configured to wick, forexample, blood away from the hole 494 and away from the perimeter of thehousing 480.

In some embodiments, the applicator base 465 and/or the patch 485 has abarrier to prevent blood from wicking from underneath the applicator400. The barrier may, for example, comprise a silicon rib or a glueseal. The barrier may be placed, for example, across a portion of theapplicator perimeter, for example, near the needle 435. Additionally oralternatively, a barrier may be placed around the needle 435, forexample, around and near the hole in the patch 485 through which theneedle passes.

910 to detect that the applicator 400 has been placed on the host, whichembodiments combinable, partly or wholly, with other embodimentsdescribed herein. The sensors are in electrical communication with asafety mechanism 920, which prevents the trigger 405 from beingactivated unless the applicator 400 has been placed on the host. Inthese embodiments, the sensors 910 and the safety mechanism 920 form, inpart, an electrical circuit. The circuit is completed if the sensorscontact the skin of the host. With the circuit open, the safetymechanism 920 prevents the trigger 405 from being activated. Once thecircuit is closed in response to the sensors 910 contacting the skin ofthe host, the safety mechanism 920 allows the trigger 405 to beactivated as discussed above. In some embodiments, the safety mechanism920 includes a battery. In some embodiments, a battery is included inthe circuit as a component separate from the safety mechanism 920.

In some embodiments, such as the embodiments shown in FIGS. 31C and 31D,the trigger 405 is electronic. For example, the trigger 405, whenactivated, provides a signal to an electric actuator 930. In response tothe signal the electric actuator 930 causes the applicator 400 to insertthe sensor into the host, to seat the transmitter 500 into the housing,and to detach the applicator 400 from the on-skin sensor assembly 600,as discussed above. In such embodiments, the signal may be provided tothe electric actuator 930 only if the sensors contact the skin of thehost. In some embodiments, the electronic trigger 405 is an electricswitch. In such embodiments, the switch, the electric actuator 930, thebattery, and the sensors 920 are part of the same circuit. Accordingly,in order to actuate the applicator 400 of such embodiments, the sensors920 must be on the skin of the host when the switch of the electronictrigger 405 is closed.

FIGS. 32-50 illustrate generally applicable features, which features arecombinable, partly or wholly, with other embodiments described herein.For example, as technology enables sensor life spans to be increased,there may be a need for long-term securement of the transmitter sensorcombination to the skin 3206 of the user. One challenge is that currentadhesive materials generally release from the skin 3206 at about 5-7days. To provide a way for long-term adhesion, FIGS. 32-35 illustrate anexample of a multilayer in-situ renewable adhesive patch 3200.

FIG. 32 shows a cross-section of the multilayer patch 3200. A firstadhesive layer 3202 and a second adhesive layer 3204 are provided. Thesensor base (not shown) will be affixed to a backing layer 3205 of thepatch 3200 opposite the skin 3206. After removal of a liner (not shown)the patch 3200 is adhered to the skin 3206 with the first adhesive layer3202. Between the first and second adhesive layers 3202, 3204 is abacking layer 3208 for providing some mechanical rigidity to the firstadhesive layer 3202.

On top of backing layer 3208 is a low-stick coating 3210, which may besilicone for example. This low-stick coating 3210 allows the removal ofthe first adhesive layer 3202 while the device is kept in place. Forinstance, after a given number of days, the first adhesive layer 3202may start to loosen from the skin 3206. The user can then peel off thebottom layer comprising the first adhesive layer 3202, the backing layer3208, and the low-stick coating 3210, as shown in FIG. 33. Whileremoving this layer from the skin 3206, the second adhesive layer 3204is exposed and subsequently adhered to the skin 3206, allowing thedevice to be worn for additional days. Preferably, the low-stick coating3210 provides enough tack to keep the layers together during the firstphase of use, such as 5-7 days, while it still allowing the peeling offof the first adhesive layer 3202. For example, silicone coatings thatare used in peel-off liners may provide satisfactory results.

FIGS. 34 and 35 are top and bottom views, respectively, of the patch3200. FIG. 34 shows the backing layer 3205 on top of which thetransmitter (not shown) is attached, while FIG. 35 shows the firstadhesive layer 3202. With reference to FIG. 34, on one side a peel-offtab 3212 is provided. The tab 3212 is used to initiate peeling off thefirst adhesive layer 3202. To ease peel-off, a so called ‘kiss-cut’ ismade through the first adhesive layer 3202 and its low-stick coatedbacking. For example, with reference to FIG. 35, a circle or spiral cut3214 can be formed so that the first layer can be removed in a defined,circling manner.

The foregoing embodiment advantageously provides an adhesive patch thatsupports long term sensor wear, and that can be deployed in-situ (i.e.without removal of the sensor).

Sensor Electronics Encapsulation

In some generally applicable embodiments, which embodiments arecombinable, partly or wholly, with other embodiments described hereinthe transmitter may be encapsulated within a molded body, for example, athermoset, plastic, polymer, glass, ceramic, or other such material. Insome embodiments, the encapsulating body may additionally oralternatively be machined or casted. Bodies formed using other methodsmay also be used.

In some embodiments, the resistance to water penetration around thecontacts may be designed to a standard. For example, the transmitter maybe designed to meet the IPX-8 Standard 6.6.1, which mandates that thedevice be protected against continuous water immersion beyond 1 m, withthe depth of immersion to be specified by the manufacturer. The IPX-8Standard is incorporated herein by reference in its entirety. However,other standards may be used instead.

The transmitter is worn on the host's body near the needle insertionsite. Thus, it is preferably easy to clean—especially if it is to beused by multiple patients. The present transmitter includes electronicspotted within a plastic shell. Three potentially challenging areas toclean are interior corners and crevices, seams around the lower edge (atthe opening) of the plastic shell, and around the electrical contacts.FIGS. 42-44 illustrate generally applicable embodiments that providesolutions for each of these challenging areas. Advantageously, theembodiments described herein are usable for multiple patients and passworst case scenario testing for cleaning between uses, for example, whenthe transmitter is dunked in a solution of bleach for about 5 minutes,after which the transmitter is tested for cleanliness using standardsknown to one skilled in the art.

With regard to the first potential challenge above, i.e. small crevices,these are difficult to clean, so if every interior corner is designedwith at least a minimum radius, it would ensure that a cleaninginstrument could access it, which is generally applicable, particularlywith any other embodiment described herein. For example, a typicaltoothbrush bristle is about 0.007″ in diameter, so if a device wasdesigned with every interior corner radiused greater than 0.0035,″ itwould be cleanable with a toothbrush (or similar cleaning brush). And inother embodiments an even larger minimum diameter such as 0.010″ or0.020″ may be provided.

With regard to the second potential challenge above, i.e. seams aroundthe lower edge (at the opening) of the plastic shell, one examplesolution provides a shell with self-leveling epoxy surface, which isgenerally applicable, particularly with any other embodiment describedherein. With reference to FIG. 42, the transmitter electronic assembly4600 is potted with an encapsulant 4602 such as epoxy, within a plasticshell 4604. The encapsulant 4602 is filled to the top of the shell 4604where it cures and bonds to the shell 4604. It forms a seamlessinterface between the plastic of the shell 4604 and the material of theencapsulant 4602. Other types of encapsulants may be used as well, suchas urethane or silicone.

Again with regard to the second potential challenge above, the shell mayhave a machined encapsulant surface, substantially the same as FIG. 42,but the encapsulant surface is machined down to a desired height for amore accurate surface flatness and height, which is generallyapplicable, particularly with any other embodiment described herein.Alternatively, the shell may have a molded encapsulant surface,substantially the same as FIG. 42, but using a mold, such as a siliconemold, to define the encapsulant surface rather than letting theencapsulant self-level.

Again with regard to the second potential challenge above, the shell mayhave a lid with a top coating, which is generally applicable,particularly with any other embodiment described herein. With referenceto FIG. 43, the transmitter electronic assembly 4700 is potted inside ashell 4702 having a lid 4704. A coating 4706, which may be anencapsulant, covers the seam between the shell and the lid. The coatingmay be applied on the entire surface of the seam, or just applied alongthe seam line. The coating advantageously covers up crevices wherebacteria could hide, making the device easier to clean.

Again with regard to the second potential challenge above, the shell mayhave a bonded lid, which is generally applicable, particularly with anyother embodiment described herein. Again, the transmitter electronicassembly is fitted inside a shell and lid where the shell is bonded tothe lid using ultrasonic welding or laser welding. If potting is used,potting material may be pre-filled leaving room for the lid. Anothermethod is to first bond the lid and use inlet and outlet ports to fillthe potting material. Materials at the inlet and outlet ports are thencut flush to lid. Alternatively, the shell may have an over-molded lid.Again, with reference to FIG. 44, the transmitter electronic assembly4800 is fitted inside a shell 4802 and potted just enough to cover theelectronics. Then the lid 4804 is formed by over-molding with a plasticmaterial. A low-pressure or high-pressure molding technique can be used.

Again with regard to the second potential challenge above, thetransmitter may be made by using an insert molding process using high orlow pressure molding techniques or liquid injection molding techniques,which is generally applicable, particularly with any other embodimentdescribed herein. The transmitter electronics would be placed inside amold and then surrounded with a polymer. The batteries would need to beprotected from the heat spike that would occur in this embodiment, sothe mold and process parameters could be tailored so that the heat spikeis tolerated by the battery. Alternatively, the transmitter may also bemade by completely encapsulating it within an encapsulant. For example,the electronic assembly could be suspended in a silicone mold, and oncecured the suspension features would be cut off. If needed the topsurface may be machined to form desired features.

With regard to the third potential challenge above, i.e. the electricalcontacts, the transmitter exterior is typically an insulator, andelectrical connection must be made from the sensor outside thetransmitter to the electronics inside, which is generally applicable,particularly with any other embodiment described herein. Typically thisinvolves installing electrical contacts through holes in thetransmitter, but this creates a seam with a small gap around the edgesof the contacts that is difficult to clean. This gap could be filledwith glue or other material, but this is a challenge to control and iscostly.

In one embodiment of a solution to this problem, if conductive polymercontacts, such as a polymer filled with carbon particles, areover-molded directly in place into holes in the shell, the over-moldingprocess will slightly re-melt the shell material, causing the contactand shell materials to weld together, thereby forming a hermetic seal,which is generally applicable, particularly with any other embodimentdescribed herein. In this way, electrical contact can be made throughthe shell and leave a smooth seam with no crevice to present a cleaningchallenge.

The foregoing embodiments provide advantages, including at least noseams or crevices to accumulate bodily fluids or debris, ease ofcleaning, and waterproofing/water resistance.

With reference to FIG. 45, in a generally applicable embodiment of thehousing 4900 including slots 4902 in a bottom thereof. The slots providea mechanism for emergency transmitter removal from a jammed applicator,so that the user can salvage the transmitter and try again with a newapplicator. After the applicator is removed from the host's skin, apaperclip inserted through the slots can be used to pull the transmitterback out of the applicator. In certain embodiments, the slots are cutthrough the adhesive patch as well to increase the ease of access to thetransmitter.

With reference to FIG. 46, in a generally applicable embodimentbutterfly stitches 5000 (also referred to as “strips”) are incorporatedinto (and under) the adhesive patch 5002, which embodiment iscombinable, partly or wholly, with other embodiments described herein.In the illustrated embodiment, two strips are provided in aperpendicular crossing pattern (“X” shape), but in other embodiments anynumber of strips may be provided in any configuration. The surfaces ofthe strips in contact with the sticky surface of the adhesive patch areonly lightly tacky. The strips are preferably sufficiently narrow tominimize interruption with the primary adhesive patch, yet provideadequate security for the user to replace a failing adhesive patchwithout accidental removal of the on-skin sensor assembly 5004. Theexisting patch is removed by peeling patch at a perforated line 5006 ata corner of the patch. A new adhesive patch with a donut shape isapplied to skin over the butterfly stitches for continued use of theCGM. This embodiment provides avoidance of re-puncturing the skin with anew sensor, mitigation of existing user nuisance (adhesive failure),uninterrupted use of the CGM, and may reduce ingress of foreignmatter/fluid

FIG. 47 is a rear perspective view of a housing 5100, according to agenerally applicable embodiment, which embodiment is combinable, partlyor wholly, with other embodiments described herein. As with previousembodiments, the housing includes a seal 5102 at a front end thereof andabutting an inner surface. The seal, which will abut the transmitter andhold the sensor when the sensor is implanted, may be constructed of anelastomeric or conformable material. In one embodiment of a method formaking the housing, the seal is overmolded with the thermoplasticportions 5104 of the housing.

FIGS. 48-51 are various perspective and elevation views of a transmitter5200, according to a generally applicable embodiment, which embodimentis combinable, partly or wholly, with other embodiments describedherein. With reference to FIG. 48, the seal 5202 at the front end of thetransmitter includes first and second spaced protrusions 5204. A spacebetween the protrusions receives the sensor when it is implanted. Withreference to FIGS. 49-51, that space creates a protected area 5206 thattraps the sensor 5208 during the process of compressing the seal againstthe housing 5210 (FIG. 51) in order to prevent misalignment of thesensor (which is illustrated in FIG. 50).

It should be appreciated that all methods and processes disclosed hereinmay be used in any glucose monitoring system, continuous orintermittent. It should further be appreciated that the implementationand/or execution of all methods and processes may be performed by anysuitable devices or systems, whether local or remote. Further, anycombination of devices or systems may be used to implement the presentmethods and processes.

Methods and devices that are suitable for use in conjunction withaspects of the preferred embodiments are disclosed in U.S. Pat. Nos.4,757,022; 4,994,167; 6,001,067; 6,558,321; 6,702,857; 6,741,877;6,862,465; 6,931,327; 7,074,307; 7,081,195; 7,108,778; 7,110,803;7,134,999; 7,136,689; 7,192,450; 7,226,978; 7,276,029; 7,310,544;7,364,592; 7,366,556; 7,379,765; 7,424,318; 7,460,898; 7,467,003;7,471,972; 7,494,465; 7,497,827; 7,519,408; 7,583,990; 7,591,801;7,599,726; 7,613,491; 7,615,007; 7,632,228; 7,637,868; 7,640,048;7,651,596; 7,654,956; 7,657,297; 7,711,402; 7,713,574; 7,715,893;7,761,130; 7,771,352; 7,774,145; 7,775,975; 7,778,680; 7,783,333;7,792,562; 7,797,028; 7,826,981; 7,828,728; 7,831,287; 7,835,777;7,857,760; 7,860,545; 7,875,293; 7,881,763; 7,885,697; 7,896,809;7,899,511; 7,901,354; 7,905,833; 7,914,450; 7,917,186; 7,920,906;7,925,321; 7,927,274; 7,933,639; 7,935,057; 7,946,984; 7,949,381;7,955,261; 7,959,569; 7,970,448; 7,974,672; 7,976,492; 7,979,104;7,986,986; 7,998,071; 8,000,901; 8,005,524; 8,005,525; 8,010,174;8,027,708; 8,050,731; 8,052,601; 8,053,018; 8,060,173; 8,060,174;8,064,977; 8,073,519; 8,073,520; 8,118,877; 8,128,562; 8,133,178;8,150,488; 8,155,723; 8,160,669; 8,160,671; 8,167,801; 8,170,803;8,195,265; 8,206,297; 8,216,139; 8,229,534; 8,229,535; 8,229,536;8,231,531; 8,233,958; 8,233,959; 8,249,684; 8,251,906; 8,255,030;8,255,032; 8,255,033; 8,257,259; 8,260,393; 8,265,725; 8,275,437;8,275,438; 8,277,713; 8,280,475; 8,282,549; 8,282,550; 8,285,354;8,287,453; 8,290,559; 8,290,560; 8,290,561; 8,290,562; 8,292,810;8,298,142; 8,311,749; 8,313,434; 8,321,149; 8,332,008; 8,346,338;8,364,229; 8,369,919; 8,374,667; 8,386,004; and 8,394,021.

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Methods and devices that are suitable for use in conjunction withaspects of the preferred embodiments are disclosed in U.S. applicationSer. No. 09/447,227 filed on Nov. 22, 1999 and entitled “DEVICE ANDMETHOD FOR DETERMINING ANALYTE LEVELS”; U.S. application Ser. No.12/828,967 filed on Jul. 1, 2010 and entitled “HOUSING FOR ANINTRAVASCULAR SENSOR”; U.S. application Ser. No. 13/461,625 filed on May1, 2012 and entitled “DUAL ELECTRODE SYSTEM FOR A CONTINUOUS ANALYTESENSOR”; U.S. application Ser. No. 13/594,602 filed on Aug. 24, 2012 andentitled “POLYMER MEMBRANES FOR CONTINUOUS ANALYTE SENSORS”; U.S.application Ser. No. 13/594,734 filed on Aug. 24, 2012 and entitled“POLYMER MEMBRANES FOR CONTINUOUS ANALYTE SENSORS”; U.S. applicationSer. No. 13/607,162 filed on Sep. 7, 2012 and entitled “SYSTEM ANDMETHODS FOR PROCESSING ANALYTE SENSOR DATA FOR SENSOR CALIBRATION”; U.S.application Ser. No. 13/624,727 filed on Sep. 21, 2012 and entitled“SYSTEMS AND METHODS FOR PROCESSING AND TRANSMITTING SENSOR DATA”; U.S.application Ser. No. 13/624,808 filed on Sep. 21, 2012 and entitled“SYSTEMS AND METHODS FOR PROCESSING AND TRANSMITTING SENSOR DATA”; U.S.application Ser. No. 13/624,812 filed on Sep. 21, 2012 and entitled“SYSTEMS AND METHODS FOR PROCESSING AND TRANSMITTING SENSOR DATA”; U.S.application Ser. No. 13/732,848 filed on Jan. 2, 2013 and entitled“ANALYTE SENSORS HAVING A SIGNAL-TO-NOISE RATIO SUBSTANTIALLY UNAFFECTEDBY NON-CONSTANT NOISE”; U.S. application Ser. No. 13/733,742 filed onJan. 3, 2013 and entitled “END OF LIFE DETECTION FOR ANALYTE SENSORS”;U.S. application Ser. No. 13/733,810 filed on Jan. 3, 2013 and entitled“OUTLIER DETECTION FOR ANALYTE SENSORS”; U.S. application Ser. No.13/742,178 filed on Jan. 15, 2013 and entitled “SYSTEMS AND METHODS FORPROCESSING SENSOR DATA”; U.S. application Ser. No. 13/742,694 filed onJan. 16, 2013 and entitled “SYSTEMS AND METHODS FOR PROVIDING SENSITIVEAND SPECIFIC ALARMS”; U.S. application Ser. No. 13/742,841 filed on Jan.16, 2013 and entitled “SYSTEMS AND METHODS FOR DYNAMICALLY ANDINTELLIGENTLY MONITORING A HOST'S GLYCEMIC CONDITION AFTER AN ALERT ISTRIGGERED”; U.S. application Ser. No. 13/747,746 filed on Jan. 23, 2013and entitled “DEVICES, SYSTEMS, AND METHODS TO COMPENSATE FOR EFFECTS OFTEMPERATURE ON IMPLANTABLE SENSORS”; U.S. application Ser. No.13/779,607 filed on Feb. 27, 2013 and entitled “ZWITTERION SURFACEMODIFICATIONS FOR CONTINUOUS SENSORS”; U.S. application Ser. No.13/780,808 filed on Feb. 28, 2013 and entitled “SENSORS FOR CONTINUOUSANALYTE MONITORING, AND RELATED METHODS”; U.S. application Ser. No.13/784,523 filed on Mar. 4, 2013 and entitled “ANALYTE SENSOR WITHINCREASED REFERENCE CAPACITY”; U.S. application Ser. No. 13/789,371filed on Mar. 7, 2013 and entitled “MULTIPLE ELECTRODE SYSTEM FOR ACONTINUOUS ANALYTE SENSOR, AND RELATED METHODS”; U.S. application Ser.No. 13/789,279 filed on Mar. 7, 2013 and entitled “USE OF SENSORREDUNDANCY TO DETECT SENSOR FAILURES”; U.S. application Ser. No.13/789,339 filed on Mar. 7, 2013 and entitled “DYNAMIC REPORT BUILDING”;U.S. application Ser. No. 13/789,341 filed on Mar. 7, 2013 and entitled“REPORTING MODULES”; and U.S. application Ser. No. 13/790,281 filed onMar. 8, 2013 and entitled “SYSTEMS AND METHODS FOR MANAGING GLYCEMICVARIABILITY”.

The above description presents the best mode contemplated for carryingout the present invention, and of the manner and process of making andusing it, in such full, clear, concise, and exact terms as to enable anyperson skilled in the art to which it pertains to make and use thisinvention. This invention is, however, susceptible to modifications andalternate constructions from that discussed above that are fullyequivalent. Consequently, this invention is not limited to theparticular embodiments disclosed. On the contrary, this invention coversall modifications and alternate constructions coming within the spiritand scope of the invention as generally expressed by the followingclaims, which particularly point out and distinctly claim the subjectmatter of the invention. While the disclosure has been illustrated anddescribed in detail in the drawings and foregoing description, suchillustration and description are to be considered illustrative orexemplary and not restrictive.

All references cited herein are incorporated herein by reference intheir entirety. To the extent publications and patents or patentapplications incorporated by reference contradict the disclosurecontained in the specification, the specification is intended tosupersede and/or take precedence over any such contradictory material.

Unless otherwise defined, all terms (including technical and scientificterms) are to be given their ordinary and customary meaning to a personof ordinary skill in the art, and are not to be limited to a special orcustomized meaning unless expressly so defined herein. It should benoted that the use of particular terminology when describing certainfeatures or aspects of the disclosure should not be taken to imply thatthe terminology is being re-defined herein to be restricted to includeany specific characteristics of the features or aspects of thedisclosure with which that terminology is associated. Terms and phrasesused in this application, and variations thereof, especially in theappended claims, unless otherwise expressly stated, should be construedas open ended as opposed to limiting. As examples of the foregoing, theterm ‘including’ should be read to mean ‘including, without limitation,’‘including but not limited to,’ or the like; the term ‘comprising’ asused herein is synonymous with ‘including,’ ‘containing,’ or‘characterized by,’ and is inclusive or open-ended and does not excludeadditional, unrecited elements or method steps; the term ‘having’ shouldbe interpreted as ‘having at least;’ the term ‘includes’ should beinterpreted as ‘includes but is not limited to;’ the term ‘example’ isused to provide exemplary instances of the item in discussion, not anexhaustive or limiting list thereof; adjectives such as ‘known’,‘normal’, ‘standard’, and terms of similar meaning should not beconstrued as limiting the item described to a given time period or to anitem available as of a given time, but instead should be read toencompass known, normal, or standard technologies that may be availableor known now or at any time in the future; and use of terms like‘preferably,’ ‘preferred,’ ‘desired,’ or ‘desirable,’ and words ofsimilar meaning should not be understood as implying that certainfeatures are critical, essential, or even important to the structure orfunction of the invention, but instead as merely intended to highlightalternative or additional features that may or may not be utilized in aparticular embodiment of the invention. Likewise, a group of itemslinked with the conjunction ‘and’ should not be read as requiring thateach and every one of those items be present in the grouping, but rathershould be read as ‘and/or’ unless expressly stated otherwise. Similarly,a group of items linked with the conjunction ‘or’ should not be read asrequiring mutual exclusivity among that group, but rather should be readas ‘and/or’ unless expressly stated otherwise.

Where a range of values is provided, it is understood that the upper andlower limit, and each intervening value between the upper and lowerlimit of the range is encompassed within the embodiments.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity. The indefinite article ‘a’ or ‘an’ does not exclude aplurality. A single processor or other unit may fulfill the functions ofseveral items recited in the claims. The mere fact that certain measuresare recited in mutually different dependent claims does not indicatethat a combination of these measures cannot be used to advantage. Anyreference signs in the claims should not be construed as limiting thescope.

It will be further understood by those within the art that if a specificnumber of an introduced claim recitation is intended, such an intentwill be explicitly recited in the claim, and in the absence of suchrecitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases ‘at least one’ and ‘one or more’ to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles ‘a’ or ‘an’ limits any particular claim containing suchintroduced claim recitation to embodiments containing only one suchrecitation, even when the same claim includes the introductory phrases‘one or more’ or ‘at least one’ and indefinite articles such as ‘a’ or‘an’ (e.g., ‘a’ and/or ‘an’ should typically be interpreted to mean ‘atleast one’ or ‘one or more’); the same holds true for the use ofdefinite articles used to introduce claim recitations. In addition, evenif a specific number of an introduced claim recitation is explicitlyrecited, those skilled in the art will recognize that such recitationshould typically be interpreted to mean at least the recited number(e.g., the bare recitation of ‘two recitations,’ without othermodifiers, typically means at least two recitations, or two or morerecitations). Furthermore, in those instances where a conventionanalogous to ‘at least one of A, B, and C, etc.’ is used, in generalsuch a construction is intended in the sense one having skill in the artwould understand the convention (e.g., ‘a system having at least one ofA, B, and C’ would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). In those instances where aconvention analogous to ‘at least one of A, B, or C, etc.’ is used, ingeneral such a construction is intended in the sense one having skill inthe art would understand the convention (e.g., ‘a system having at leastone of A, B, or C’ would include but not be limited to systems that haveA alone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). It will be furtherunderstood by those within the art that virtually any disjunctive wordand/or phrase presenting two or more alternative terms, whether in thedescription, claims, or drawings, should be understood to contemplatethe possibilities of including one of the terms, either of the terms, orboth terms. For example, the phrase ‘A or B’ will be understood toinclude the possibilities of ‘A’ or ‘B’ or ‘A and B.’

All numbers expressing quantities of ingredients, reaction conditions,and so forth used in the specification are to be understood as beingmodified in all instances by the term ‘about.’ Accordingly, unlessindicated to the contrary, the numerical parameters set forth herein areapproximations that may vary depending upon the desired propertiessought to be obtained. At the very least, and not as an attempt to limitthe application of the doctrine of equivalents to the scope of anyclaims in any application claiming priority to the present application,each numerical parameter should be construed in light of the number ofsignificant digits and ordinary rounding approaches.

Furthermore, although the foregoing has been described in some detail byway of illustrations and examples for purposes of clarity andunderstanding, it is apparent to those skilled in the art that certainchanges and modifications may be practiced. Therefore, the descriptionand examples should not be construed as limiting the scope of theinvention to the specific embodiments and examples described herein, butrather to also cover all modification and alternatives coming with thetrue scope and spirit of the invention.

What is claimed is:
 1. A device for applying an on-skin sensor assemblyto a skin of a host, the device comprising: a housing configured toreceive an electronics unit, wherein the electronics unit is configuredto generate analyte information based on a signal from a sensor; asensor insertion assembly configured to insert the sensor into the skin,the sensor insertion assembly including a needle configured tofacilitate inserting the sensor, a needle carrier, and a pushrod,wherein the sensor insertion assembly comprises a wheel configured torotate about a fixed point, the wheel including a first tab extending inan axial direction from the wheel, a flange extending in a radialdirection from the wheel, a torsion spring configured to cause the wheelto rotate, a stop configured to interrupt rotation of the wheel, whereinrotational movement of the first tab translates into a linear movementof the needle carrier to insert the sensor into the host; and a triggerconfigured, in response to being activated, to cause the needle carrierto automatically actuate toward the skin to insert the sensor, andsubsequently to automatically actuate away from the skin to withdraw theneedle from the skin, wherein the pushrod prevents the sensor fromactuating away from the skin, wherein the flange is configured toprevent rotation of the wheel prior to the trigger being activated, andwherein the trigger includes a second tab extending from the triggerthat is configured to bear against the flange prior to the trigger beingactivated.
 2. The device of claim 1, wherein the pushrod is disposedwithin the needle prior to activation of the trigger.
 3. The device ofclaim 2, wherein the trigger is configured to cause the needle carrierto actuate with the pushrod towards the skin.
 4. The device of claim 3,wherein the pushrod is configured to disengage from the needle carrierwhen the needle carrier actuates away from the skin.
 5. The device ofclaim 1, wherein the sensor is configured, after insertion into thehost, to be surrounded by an elastomeric seal, and wherein theelectronics unit is configured, in response to the electronics unitbeing released from a lock, to compress the elastomeric seal to securethe sensor and to form a seal around the sensor.
 6. The device of claim1, wherein the device is configured to provide one or more tactile,auditory, or visual indications that the electronics unit has beeninserted into the housing to the extent permitted by a lock.
 7. Thedevice of claim 1, wherein the sensor insertion assembly is configuredto insert the sensor into the host at a maximum velocity influenced by acentrifugal brake.
 8. The device of claim 1, wherein rotation of thewheel is configured to induce linear motion in the needle carrier. 9.The device of claim 1, further comprising a trigger lock configured toprevent activation of the trigger.
 10. The device of claim 9, whereinthe trigger lock is configured to be pivoted upward by contact with theelectronics unit to allow activation of the trigger.
 11. The device ofclaim 1, wherein a surface of the second tab that is configured to bearagainst the flange has a predetermined angle that causes the wheel toapply an outwardly directed preload to the trigger.
 12. The device ofclaim 1, wherein activation of the trigger causes the second tab to moveto a position below a plane of the flange.
 13. The device of claim 1,wherein the needle carrier includes a channel configured to receive thefirst tab.
 14. The device of claim 13, wherein the first tab isconfigured to move within the channel to impart linear motion to theneedle carrier.
 15. The device of claim 14, wherein the wheel isconfigured to rotate at least 90 degrees after the trigger has beenactivated.
 16. The device of claim 15, wherein the wheel is configuredto rotate at least 180 degrees after the trigger has been activated. 17.The device of claim 14, wherein the needle carrier is configured totranslate linearly away from the skin to withdraw the needle from theskin.
 18. The device of claim 1, wherein the trigger is configured, inresponse to being activated, to cause the electronics unit to secure tothe housing such that the sensor electrically contacts the electronicsunit.
 19. The device of claim 1, further comprising a front cover, andwherein the trigger is configured to be activated by being pushedinwardly with respect to the front cover.
 20. The device of claim 1,wherein the needle is configured to carry the sensor.